TSP #133 - Keysight UXR 110GHz BW, 256GS/s, 10-bit Real-Time Oscilloscope Teardown & Experiments

hi welcome to signalpad i have a really special episode for you guys today i have the privilege of introducing you to the keysight uxr series real-time oscilloscope this oscilloscope isn't just a little bit better than the study art it's a giant leap forward it can do 256 giga sample per second with 110 gigahertz of analog bandwidth on four channels simultaneously and it does that with a 10 bit resolution a to d converter and it doesn't matter how many charge channels you have active because it does 256 gig sampling all the channels at the same time this means that it captures processes displays and stores over 10 terabit per second of information in just this one box it's just unbelievable in order to get to this kind of specification they've had to innovate at every layer of the design and everything had to be custom made from scratch from the front-end connector to the pre-amplifier to the samplers to the a2d converters and even to the ic that interfaces the memory to the hdd converter had to be completely custom made in order to accommodate this massive amount of data that's being captured they also had to create their own calibrator module with nist calibration certificate which they can ship to you and you can calibrate your scope directly in the lab there's really nothing else like this and the fact that they have gone to this point is really amazing if i told you a couple of years ago these numbers you would have never believed it now this 10-bit atd converter which is sitting at the heart of this scope is the same one that's in the asterisk which i did a full teardown and review and that that's been refined and upgraded to be put in here now not only are we going to take a look at it and see how it behaves i'm going to take it apart well not quite take it apart but they've really sent me the acquisition board and they've sent me the front-end sampling modules i'm going to take off the part look at it under the microscope and really give you a detailed view of how it works what kind of engineers gone into it i'm going to take a look at how they've accomplished this massive amount of bandwidth it's actually 113 gigahertz which is extraordinary there's so much you can do with this there's it opens up test and measurement capability for optical coherent communication and even wireless communication if you want to capture many wireless channels at the same time like nothing else before so i'm really eager to take a look at it it's going to be a long video broken into a few sections you can look at the description to jump to the section you want this is still a prototype so for really detailed testing we're going to have to wait a little bit longer but i still do a couple of experiments with it which i think shows you how amazing it is and what it can be done with it so without any waiting let's go check it out so before we look at the architecture of the new oscilloscope i think it's worthwhile to appreciate how people have been doing this kind of high frequency sampling in the past or at least up to this point now tektronix likroy and keysight all have employed various techniques to overcome the limitations of time interleave a td converters for example lacroix does the digital bandwidth interleaving which is something that they have invented when i did the full teardown analysis of their scope we talked extensively about how that architecture works by splitting the frequency into two bands and then looking at the esp and combining them now keysight has their own real edge technology which works in a somewhat similar way it has some differences between their implementation and the electro implementation and of course the tektronix asynchronous timing to leave architecture which came a little bit later also uses some tricks on how to with dsp to correct how they sample the front end by using completely asynchronous sampling now all of these techniques they work to some extent but they all suffer from some basic limitations these these techniques of combining signals afterwards in dsp always has the limitations of noise being overlapped the tones being generated at the boundaries where frequencies overlapping it's a quite difficult a problem and dsp intensive problem to solve this and they work and they have been demonstrated up to about 70 gigahertz or so from all of these companies but what keysight wanted to do here is to go back to really do time interleaving basically truly do 264 giga sample per second really and and get all the bandwidth from the front-end process by the single asic all the way up to 110 gigahertz and that's exactly what they have done here and this is a very basic representation of their instrument it's very simple it's just pre-amplifier samplers and other samplers and then buffers and adcs exactly how a time interleaved architecture would be like and this time into leave architecture is time interleaved in several layers uh first is timing to leave between chipsets and then within the chip says the time interleaved between adc's and we'll talk about that in detail but really the architecture is pretty straightforward and this is what the architecture of pretty much every oscilloscope and that relies on time interleaving architecture without doing any fancy frequency interleaving or anything like that this is what it's going to look like so now that we know this let's go ahead and take a look at these blocks a couple of these pictures here for example the front end is pretty interesting the acquisition board is interesting and i have those and let's go take a look and see how they're made and here we have all the hardware required for 256 giga sample per second of data acquisition storage and processing there's a lot here to talk about and we're lucky enough to have all the hardware to take a look at it now here's the main 110 gigahertz front-end sampler module here's the two-channel version for the lower models we'll talk about it as well and of course the entire acquisition board adc's the chipset that interfaces with the adcs and the hypercube memory module which is all the way at the back and we'll take a look at these in detail now what's amazing is that we're also given the ability to take a close look at the front-end module where all the magic with 110 gigahertz of bandwidth and sampling happens you can see here that the back of the lid we have rf absorbers strategically placed on top of the rfi season some of the critical traces this is to be expected because everything here is in a faraday cage you may not be able to see through the camera but we will be able to see when we look at it closely that these walls are all coming off the surface of the pcb and you're creating all these cavities and if you're not careful you're going to create second modes in there and it will be such a high quality factor you will get resonances and potentially even oscillations so they've obviously thought of that this is what they do all the time now we're going to take a close look in the front end i'm interested to see how the analog data is handled how is the clocking handle clocking for a to d converters is critical if you're not if you don't have a line clocks but for these samplers you're going to have tones and spurs all over the place in the spectrum after the data converters so there's a ton of engineering that's gone into this as well as multiple technologies used to build this front-end so i'm going to take a really close look at this and analyze it in a way reverse engineer it to some extent and then we'll jump into looking at a data converter and the chips that they've created for the interface the dsp there's a ton of stuff in here and of course the two-channel version so without keeping you waiting let's go and take a zoomed in view of this and i'll go over it step by step and see how it works so let's take a look at this front end and really analyze exactly what's going on and there's a lot of things happening here but we should kind of break it down step by step i think the easiest place to start is just the front-end so the input signal enters the device from here this is going to be a one millimeter connector in the hundred and ten gigahertz version of this instrument now before this connector there is an electromechanical attenuator and that electromechanical antenna sits between the front panel connector and the sampler module here that you see and the reason they put the electromechanical attenuator is because there is no way to get the massive dynamic range required from you know a volt per division all the way down to a millivolt per division going directly into the front-end amplifier so they divide the task of attenuation between the mechanical and the solid state attenuator or the amplifier that's the front and this is common this is done all the time however you have to appreciate the difficulty in doing this because the loss and the frequency flatness of the mechanical attenuator the interfaces between the connectors and the module all of those are going to make it difficult to get 110 gigahertz bandwidth signal into this module so they have custom design all of these these modules are made to each other there's no cable in between everything's assembled mechanically together so having said that let's assume that the 110 gigahertz signal simply enters this front-end module after the mechanical attenuator we have a very small trace then we have two amplifiers in a row there's two chipsets here these are indium phosphite front-end amplifiers and vgas so your solid state valuable gain amplifier control and the front-end amplifier that handles 110 gigahertz of signal is all done here the system linearity the system noise and the performance is determined by these front-end amplifiers you can imagine how difficult it is to design this to have such a noise to actually get anything meaningful from the a2d converters that follow after many stages the amount of components that are actually cascaded before you hit the a2ds is staggering and to be able to meet the linearity and the noise for that is really quite amazing so having said that this indium phosphide front-end amplifiers are designed by keysight in their own foundry they have their own foundry that make indium phosphite devices up to 600 or 700 gigahertz ftf max i can't quite remember the exact numbers but you know needless to say this is a very fast process so now signal coming out of here at this point is still a 110 gigahertz signal now there's also a path coming out here all the way going into this device here this is an edge trigger this is a 24 gigahertz edge trigger device it's actually not really used in this because 24 gigahertz of edge trigger is kind of a legacy architecture for being able to detect edges up to 24 gigahertz but when you have 110 gigahertz of bandwidth you don't really want to use the 24 gig edge trigger anymore this entire oscilloscope uses a digital trigger so all of that is handled by the dsp custom digital asic that they have designed that follows the a to d converts we'll talk about that when we get there but the hardware for an analog 24 gigahertz edge trigger is still present here the signal after that goes into our first sampler now here's the first really complex uh device that is also an indium phosphide is presented now this device is going to take her 110 gigahertz signal is going to sample it with a 64 gigahertz clock in four phases in order to generate four signals coming out each of them now having bandwidth of up to 32 gigahertz this is how you get the reduction in required bandwidth as the stages follow on this is again a normal architecture for time interleaved data converters so therefore we will have four paths one path over here one path over here one path over here and one path over here so we would expect these four paths to go into the next stages of samplers in order to be able to further break down the bandwidth so that you can actually use the a2d converters inputs so how do we do this 64 gigahertz for phase sampling that itself is really difficult so for to understand that we have to go from the side where the clock is now generated now there's an ic over here which you can barely see the edge of this is a hittite part this is a 12 to 16 gigahertz to up to 17 gigahertz amplifier it has a p1 db of 26 dbm so you can put out tons of power which is required because they're going to divide that clock signal further down now it appears that the 16 gigahertz system clock comes from here but if i understand correctly that itself is generated from an eight gigahertz fundamental clock which is spread throughout the entire chassis connecting all the different samplers and connecting all the different atd converters to a common synthesized clock which again is all designed by keysight generating an eight gigahertz clock clean enough to be able to feed 256 giga sample per second equivalent sampling is really challenging now i don't have that board unfortunately but needless to say it's you know in the in the 10 femtosecond range clock which is really amazing so now that it doubled that apparently at some point and then we get the 16 gigahertz clock and there is a first power splitter here that power splitter splits the signal into two parts one side of it goes in here now this disappears into the board but you can kind of roughly uh see where it would go it would have to come all the way over here and this goes underneath this module and then comes out of here and pops into this so now you have a 16 gigahertz signal going into this chain over here first they do some some filtering to make sure you know there's only a single tone and then they double it once here so that times two over here that's doubled so now it's at 32 gigahertz once again they filter it very carefully and then they double it again one more time now we are sitting at 64 gigahertz now single is still single-ended which means that it needs to become differentials there's after some filtering there's a hybrid here you can see very closely the hybrid splits the signal into two pieces now that you have two signals that are in 180 degree out of phase and it appears that they put them through two separate amplifiers here so they have two single nano distributed amplifiers again this is all in indium phosphide now you have a 64 gigahertz signal on one side and a 64 gigahertz signal on the other side so you get yourself a differential a 64 gigahertz signal going into the front end indium phosphite sampler but that's of course not in four phases you need to generate four phases from 64 gigahertz normally if you're in a silicon germanium process or in a cmos process that's not too difficult but in indium phosphide you gain linearity and noise and dynamic range but you lose complexity of integration so making phase shifters that are adjustable in indium phosphide is quite difficult now i happen to know that the way they do this is that they double the 64 gigahertz yet again to 128 gigahertz and then they process that back down in order to get the four phases which is a common technique you can use if you have tons of bandwidth and tons of frequency content you can do this in a very fast process going the opposite direction just so that you can create your phases so now you have four phases of 64 gigahertz in here which you can use to sample the front-end 110 gigahertz signal into four sections so all of that is again fully key side design all of these filters every single component you see here has been custom designed to make this happen you still need phase shifters inside the front end because you need to make sure that the alignment between the 64 gigahertz clock in four phases is good and they do take care of that again inside the three five process amazing stuff so now you have all these four signals now you can get away from indium phosphide and and make the complexity more and create signals that can be processed in a silicon germanium process you don't need as much bandwidth anymore the bandwidth of these signals coming out of here is no longer uh 110 gigahertz is only up to 32 gigahertz now all these traces that you see these are all thin film deposits these are all again done by keysight this is all completely custom made and you can see individual cavities here this is this has a depth of a couple of millimeters so when i put the lid on top of this all of these are in fahrenheit cages and you can see that they isolate the traces from each other and these are high bandwidth very low skew good group delay paths created to make the signal as nicely preserved as much as possible before it hits the next samplers there now going forward let me change the color here so that we can do the second stage with a different color all right let's take a look at the what happens after that let's go back to the clock so now the other path of the clock the other 16 gigahertz clock goes into this hybrid here which then further splits the signal into four so now you got one two three four pads each of them 16 gigahertz again you can use this to feed the samplers of the stages that follow so now following over here we go into this here's the another sampler here is another sampler going over here is the third one and going over here here's our fourth one now these clocks that are disappearing into the pcb you can see the trace is over there one of them pops over here the other one pops over here this one where does it go right there and the last one goes all the way here and pops out of here and if you look closely you can see that they take the 16 gigahertz signal and not only do they filter it but they also passively create a 180 degree hybrid here so there's a balance in there plus the filter feeding the 16 gigahertz clock into the sampler here now this is a silicon germanium sampler you can generate four phases from the 16 gigahertz in here fairly straightforward so there's four phases of 16 gigahertz sampling the front-end signal coming over here at a bandwidth of up to 32 gigahertz which then creates four lanes one two three four out of each of the samplers so you can see that this splits into four yet again and four over here one more time and then four over here one two three four and then four over here as the last one so now your 110 gigahertz front-end signal has now been broken into 16 differential pairs and these 16 differential lines can now be fed into the a to b converters because now they're low enough in bandwidth each of them has a bandwidth of just under eight gigahertz now 16 times eight is 128 gigahertz the bandwidth of the scope is limited to about 113. so each of these process a little bit less than eight gigahertz of signal but now that you have this you can feed that directly into an a2d converter all you need is that your a d converter must now accept four lanes uh each of them up to eight gigahertz of bandwidth now if you do that which means that your a2d converters would have to be each 64 giga sample per second which is exactly what it is now the a2d converters one here second a to b here third a to d here and fourth a to d here all have to work in parallel so four times 64 you get 256 giga sample per second but don't don't be fooled by the fact that you keep splitting these signals and therefore you make the job of the a to the converter easier the isolation and the alignment and the matching between these paths is critical because if you don't have matching between them then you're going to get spurs in the spectrum of the a2d converters you can't just split the signal without worrying about how much phase noise you have how much phase alignment you have how much amplitude balance you have that's what the magic of this front end is is to be able to take 110 gigahertz produce a signal that can actually be processed by 64 gigahertz per second a 2d converter now just the adc itself at 10 bits with 64 giga sum per second is itself an engineering marvel because it's not easy to make that but you can see that they've broken the front end a little bit differently than it is in the s series oscilloscope which i did a full teardown and review of before this is the same adc that has been upgraded and refined for this application so you can see how they use that and they just tweak the front end with new devices and new configurations in order to enable 256 gigs per second sampling now if you look closely again the adc inputs from each other are fully isolated and this reason is because it is a little bit easier to handle crosstalk within each adc then between the adcs so the isolation between the lanes of these ones coming out is very important i also want you to appreciate how difficult it must be to isolate the clock from leaking into the a2d converters because you have 16 gigahertz clocks everywhere in multiple phases you have multiple multipliers and doublers which create harmonics and intermodulation products all of these things coexist in this front-end module all of which have to be filtered properly in order to make sure that they don't feed into the a2d converters so really is extraordinary a ton of engineering has gone into making this happen you can see custom packaging there's devices from different technologies is is amazing and what is also interesting is everything is wire bonded now they don't use flip chip technology anywhere here because you can calibrate some of those effects out and with clever design you can get away with using wire bonds even up to 110 gigahertz is which itself is quite interesting to see so there it is that's the front end so now you have an idea of what happens to the 110 gigahertz signal and how does it end up being fed into four adc's at 64 giga sample per second so now we can go ahead and take a look at the acquisition module and keeping in mind exactly what is happening here and see how that signal is processed by the a2d converters and here is the 256 giga sample per second acquisition board it is massive and it has so many components on it so many devices designed by keysight now keep in mind there are four of these inside a four channel oscilloscope that's because that's how you're going to get 256 gigahertz per second 110 gigahertz per channel regardless of how the channels are configured so it doesn't matter if you have one channel on or if you have four channels on you have one of these dedicated per channel that's one of the reasons why it's 1.3 million dollars because you have so much independent redundant hardware to get the performance per channel totally unaffected by how much data you're collecting so as we said this needs to have four 64 giga sample per second a 2d converters in order to be able to to get to 256 gig sampling and with the 16 inputs coming from the front end sampler i just showed you so here's one two three four a to d converters and these are the each of these are 64 gig 10 bits with four inputs you can see some of the traces with the microstrip or strip lines that are going into it there's a front-end high-speed connector and an alignment pin that allows you to interface with the front-end sampler so all the analog signals have to travel as little as possible and they've come up with this solution with this connector there is a front-end sample there modulator this thing is quite heavy to lift oh i have it the other way around like this and this simply plugs in to here like so there it is that's one channel and this then has to connect to the front panel of the instrument so the electromechanical antenna sits right over here and right after that is the front end of the instrument itself so then you stack four of these so you can imagine the thermal management and the mechanical management of this itself is quite a nightmare now even though you have four 64 gig a2d converters here how do you deal with the data coming out of these because each of these is at 64gb 10 with 640 gigabit per second of data needs to be handled not only that these are all working together so you need to have the alignment the calibration all the coefficients to handle with the channel channels mismatches and channel frequency group delay variations all of those parameters have to be somehow handled directly from the after the a to d converters and more importantly what about the trigger this thing has a full digital trigger per channel up to 110 gigahertz which means that you need to also be able to do that live on the data as it comes in of course you can't dump that data to a cpu there's no way which means you have to create a custom digital signal processor chipset to handle all of that and of course that's what they've done one two three four each of these is independently connected and working together at the same time to each of the a to the converter so everything you see under these eight heat sinks that's keysight technology designed and manufactured by them just so that you can package by them just so you can put it on this board now after that you need to put the data into some kind of memory the data is coming in at huge rates here and the only way to handle that is you have to use a very fast memory like a hypercube it's a 3d integrated memory these are made by micron there's four of them again and these actually have more than a two gigabyte of of storage or two giga sample per of storage there's much more but the scope doesn't use all of the memory only uses a fraction of it because of the 32-bit architecture you can only address 4 gig in total so anyway that's a minor detail and perhaps something that they will change in the future but there is memory available more than what is expected for the scope so now we have this chain i actually have the ics for each of them and we should be able to take a look at it and i'll show you that in just a second to show you what goes into those and they're decapped so we can even look at what's underneath them although you're really not going to be able to see very much because it's all flip chip technology so take a moment and appreciate what's happening here how much technology is involved because the front has this indium phosphide then we're going to get to silicon germanium and then there is a two chips inside the hd converter silicon germanium and then 65 nanometers cmos and after that you go into a dsp which itself is either 24 or 28 nanometers cmos so they've designed across so many technologies to make this happen this is a lot of work and it is really amazing to see how many engineers have to work together and how complex this system is so let's look at it a little bit from the edge here this is a fairly thick board as you can imagine because these ics have a lot of bga balls on the back of them when you look at the density of this package here and that's the digital processor part so then all of that of course has to go into the board so then this might be a maybe a 32 layer board not quite sure it's a power connector massive massive power connector here on the left some digital connectors on the other side and check this out this is just beautiful a lot of linear technology dc-dc converters these are the best pretty much you can buy in the world you can see some of the other traces going in there's some cable cut here it's most likely they were injecting clock because the clock also needs to go into these atd converters the clock needs to be synchronized aligned to the clock of the front end oh it's just an absolute nightmare i'm going to zoom in a little bit so you can see some of the beautiful layout that is done here i mean take a look at these decoupling capacitors is just insane and they're all at 45 degree angle because you can't you can't fit them otherwise this thing is is absolutely beautiful i think i'm gonna have to take a couple of pictures of these and make a wallpaper out of this it's just amazing to see how much is going on at the back of this board so all the power handling all the calculations for how to make sure there's no noise coupling there is what do you do with the digital noise what do you do with analog noise it's just crazy that the board this board design is is wonderful so now we can flip it back over here and let's take a look at inside the package of the a2d converter now this is the same a2d converter as the s-series scope let me find a good angle here so we can also zoom into it a little bit more there it is so this a2d converter itself is a two-chip module which is a front-end silicon germanium module that front-end handles the amplifying and aligning and whatever it is required to feed the signal into the 64 giga sample per second four channel input a 2d converter which is in 65 nanometer cmos it's a very straightforward uh packaging nothing unusual there you can see the front end they have done a little bit differently in terms of where to place the balls to create good signal integrity and so on so two chip solutions sigi and cmos a hybrid adc module same thing you will find directly in the s series scope which looks quite nice so then now if you if you're keeping track we have a front-end indium phosphate amplifier front-end indium phosphide sampler sigi sampler cd pre-amplifier 65 nanometer cmos that's how the data ultimately gets to the a2d converter that's just crazy crazy and then if you can also take a look similarly to the chipset that the airspeed which is actually right on top of underneath this heatsink you can take that cup cap off that's a fairly large ic there this is a fully digital ic which interfaces with the a2d converters as i said tons and tons of ios in the back there very nice very nice design as to be expected it looks like a regular flip chip bga package there all of this heatsink of course has to come from the top flip chip gives you that advantage to get the heat from the top of the ic which is most efficient and uh these are most likely some test uh test ports here during during factory testing maybe it's interesting to see what they're doing here around the border there and yeah it's it's 28 diameter 24.99 we are not sure but it has all the interfaces required to grab data from day to day and to interface with the hypercube memory from micron so there it is that's uh that's kind of what it looks like to get from a 110 gigahertz analog input all the way to 256 gigahertz per second digital sampling there now because this front-end module is kind of designed in such a way to accept broken-down signals down to you know eight up to eight gigahertz per channel it means that you can take advantage of the architecture of this sampler and break it into two and make two 128 giga sample per second front end so you can operate this half at 128 gig and this app and 128 gig and created two channel other scope with half the sample rate if you don't need to go to 110 gigahertz and that's exactly what they have done and that's what the purpose of this other sampler module is if you look at this other sampler module it has the same interface connector so you can connect directly to the same front end here and the only thing that's different is that instead of having the indium phosphite you don't need any of phosphate anymore because the front-end bandwidth can be limited to 32 gigahertz if you don't need to go above 32 gigahertz well we can give you two channels like this and you can have samplers that are the same sticky samplers which are much simpler now to work with and the front end can be entirely done in silicon germanium reduces the cost significantly the components are much much fewer everything is flip shipped over here there's no wire bonding this is all reflow process makes things significantly lower cost and now you can have two channels up to about 32 gigahertz a bandwidth or so but then each of them can be 128 giga sample per second now this is the first time in history ever that you have a front-end module that can be configured in such a flexible way all the way up to 256 giga sample per second so if you buy a scope that has this in it you can keep upgrading it by just simply changing the front-end module by sending it to factory they'll just change this but they'll keep this piece in your scope so the same chassis with the same serial number can be upgraded across a huge range of bandwidths as your needs change and that lowers the ownership cost of the ecosystem that's one of the key factors here is that you don't want to have to keep throwing everything out and you see here's the same clocking scheme used in the back so it's essentially identical to the other one all you need to do is just change the front end uh back to this one if you want to go to higher frequencies everything stays the same and then the software handles it really quite beautiful amazing amazing stuff going on here the amount of engineering that keysight engineers should really be proud to put something out here on the market so there it is that's a detailed look at how it works how it compares and how it's manufactured but now the fun part let's go turn the thing on put some signal into it and see how it behaves so right now we have the scope at 500 millivolt per division which is the maximum input signal and this is absorbed by the front end and mechanical attenuator but we can go all the way down to two millivolt per division in hardware and there's a one millivolt per division which is the further amplification that's done internally so i can go all the way down to a two millivolt per division and this is the the best that the hardware can do so now the mechanical attenuator is at zero db attenuation and the front-end indium phosphide pre-amplifier is at the maximum gain this is going to be the the lowest noise the scope is going to be able to support now traditionally this noise goes up for some of the other competing products but they've kept the noise really low and we'll take a look at that it's really amazing and right now we're sitting at one micro second per division over here but check out how far you can go it's crazy so we can continue to go forward right now we are at uh one nanosecond per division and i can keep going all the way to one picosecond per division one of these horizontal divisions is one picosecond that's an extraordinary thing to see and this is what you get from 256 giga sample per second so let's go back all the way to one microsecond and the reason the reason i want to go to one microsecond is because i want to capture a lot of noise and measure that noise by doing an rms calculation directly on it so right now the scope is set to 113 gigahertz full bandwidth and 113 gigahertz of full trigger bandwidth so this is as much noise you can ever collect from the front end because this is full bandwidth at play here so let's go ahead and see how much noise that is i've already set that up here there it is so the rms noise for a one microsecond period at 256 giga sample per second over 113 gigahertz of bandwidth is on average about just under 700 micro volts rms that's wonderful that's amazing to see and it's at minus 50 dbm that's the in dbm equivalent of it this is with nothing connected to the input of the oscilloscope as you can clearly see now this noise is for the full bandwidth however if you don't need 113 gigahertz of bandwidth you can reduce this equivalent noise by filtering everything that you don't want it can be all done in dsp because the adcs are capturing the entire bandwidth all together at the same time anyway and there is no hardware filter in front of this it's just not really possible to put anything in the front of this and that wouldn't degrade the performance so they just capture everything and process and deal with it in the digital dsp chipset that i have designed directly after the a2d converters so we can go ahead and reduce the bandwidth let's set the bandwidth from a let's say 113 gigahertz set it to 70 gigahertz and keep an eye out on this number now we are sitting at 50 at 500 micro volt rms so you can see that the noise is gradually going to come down as you reduce the bandwidth so if you don't need 70 gigahertz no problem we can try 30 gigahertz here you go at 30 gigahertz we're going to be down to about 300 micro volt rms which is tiny it's it's by far the best there is in this kind of performance now if i go all the way to one gigahertz of course you can see at one gigahertz the noise almost completely disappears we're sitting at 73 micro volt on average or about 0 the mean is about 80 micro volt on average now keep in mind that this 80 micro volt average noise is the noise from a front end that supports 113 gigahertz of bandwidth if you were to build a front end only for one gigahertz of bandwidth sure you can build that perhaps even less noise and you can see that in the s series scope but this is the same front end that is capturing 113 gigahertz of bandwidth and for that to go this low is just crazy and it's amazing to see that the process and the design of the front-end amplifier and of course the noise from attenuators and everything is is quite good and this is how they get some of the performances that they are able to do and i'll show you that at the very end of the video by doing ffts and so on and you can see exactly how much noise can be captured so from the noise point of view this is amazing and i will show you the the enob as a function of noise as well one of the other very interesting thing about this design is that the effective number of bits of the scope scales with the bandwidth you're using and that's because it's purely limited by the noise and it's not limited by harmonics and by distortion and because if it was limited by distortion even if you reduce the bandwidth you wouldn't be able to get rid of it that's a huge plus for this scope that you can change the enop as a function of bandwidth and we'll show you that plots at the end now having said that well how do you calibrate the scope like this you know you spend a 1.3 million dollars you get a four channel scope on your bench and now you want to calibrate it and align all the channels to each other and make sure that the frequency response and the group delayed response of all the channels are matched you would need a 110 gigahertz source and you would need a nist calibration in order to do this and of course you don't want to send the scope to keysight every time you need to calibrate it that wouldn't be practical so what they have done is that they have created a probe that plugs in directly to the front and that probe is their own design that creates a very sharp edge that allows you to calibrate the scope to the output of the probe and i'll show you that probe in just a second and tell you how it works it's a good clever way of being able to do calibration directly in your lab so you never have to send the unit back to get it miscalibrated and here's a close look at the calibrator now the front end of the calibrator directly mates with the front connector of the unit it's a one millimeter ruggedized connector and everything in here and this module is designed by keysight it has their own three five process components and i will show you from a photograph and we'll talk about how it works now as i said this is a nist calibration unit meaning that the exact response of it up to the edge of this connector is stored in here and once you connect this to the unit it will download this response into the instrument and the instrument will try and match this response from the measurements it's getting so it doesn't even matter but that response is as long as it has enough frequency content to meet the 110 gigahertz requirement but that's pretty clever and a good simple way to do this as long as you can create this device and i'll show you what that is in just a second and now here are some of the connectors that it comes with the unit as well this is for example to convert the ruggedized one millimeter connector to a v connector there's also k connectors and here's a one millimeter to one millimeter connector and the advantage of these is that you will just basically age these connectors and in case something breaks it would be these ones as opposed to the front of the unit itself these are much cheaper to replace than of course the front end connector of the instrument it will be significantly more difficult you have to send it into keysight but these also come with the uxa the spectrum analyzer as well so let's go ahead and connect this to the scope but before that let me show you what's in it and exactly how it works and here is what is inside this calibrator probe here so this module that we were just looking at this is what it looks like on the inside so there is an ic in the front which take we'll take a look in just a second and there's a signal deck which can be fed directly into this ic now this signal is going to come from the auxiliary port of the oscilloscope itself which generates a square wave and the rise time of that square of it is nowhere close to 110 gigahertz equivalent bandwidth so you're going to have to increase the edge sharpness and reduce the rise and fall times before it becomes useful for doing this calibration up to 110 gigahertz which is exactly what this is so after a little bit of filtering over here the square wave that's coming from the auxiliary port is going to go through this indium phosphide limiting amplifier there are multiple stages of limiting amplifier in a row here and every time you limit this with very high gain and very high accuracy you reduce the rise and fall times and they do this a couple of times until until it's super sharp uh with the rise time only a couple of picoseconds and then they feed that out from the connector to the scope now this is really impressive this actually means that the rise and fall times right here at the edge of the ic is even more because without this interface and the connector and everything because all of that is going to of course further limit the bandwidth it's quite difficult to get all of that working quite nicely so having said that this is what's inside this all designed by keysight again from scratch just for the purposes of being able to do this nist calibration directly on this oscilloscope itself which is really quite impressive so now that we know how it works internally we can go ahead and connect it to the scope and see how it behaves and here i have the calibrator directly connected to channel one of the instrument and the interface to the front of the scope the probe interface is also connected and the auxiliary output of the scope which generates the square wave directly goes to the calibrator now as you know as i showed you what's inside that the calibrator here those edges coming from the auxiliary are going to be continuously sharpened up until to a few picoseconds so that we can calibrate this scope with it and this also shows you how what kind of fast edges can actually be captured here by the scope right now we're looking at 512 million points 200 microsecond per division we can see the square root but we're looking at it from really really far away so we're going to zoom in and see how fast those edges actually are so let's go ahead and see what happens so i'm going to go all the way down so right now we're at one microsecond keep zooming in five nanosecond one nanosecond and we're going to go here there's 10 picosecond per division and check it out we're looking at a 3.3 picosecond edge that's how fast and how sharp those edges actually are and this is why you're able to use this as a missed calibrator the exact group delay frequency content phase information that's coming out of the calibrator has been transferred to the scope and the scope is going to calibrate itself and change the coefficients required to match that exactly so the calibration plane of the calibrator is at the edge of the connector and the plane of the measurement of the scope is at the connector of the scope itself and those two are going to match perfectly and that's how you get this calibration on the channel and it looks amazing i mean to get a a 3.2 picosecond edge measured live on an oscilloscope it's never been done before for a real-time oscilloscope and we can also go ahead and do a calculation and do a quick function to show what the pulse response looks like and here's the pulse response and you can also see even the ripple the ringing that comes from the sharp edge just simply because the interface is not perfect it doesn't matter by the way that it's ringing because that ring is included in this calibration performance so it doesn't matter what it looks like it just needs to match that response exactly and that's the beauty of it each calibrator can be a little bit different but you can still perfectly calibrate the scope as long as there is a certain performance that each calibrator meets and you can see the ripples here and look at this impulse response here this is in giga volts per second that's how sharp this edge is this is amazing to see this and this is a really good way to quickly do this and not only can you do the calibration for the phase and group delay and frequency response of the channel itself this also aligns the channels to each other which is another important thing because you have a single source coming in and that source is self-aligned to all the channels therefore and that's that's how you can get everything calibrated to each other which looks great so here's the setup to produce a very high frequency signal to the oscilloscope now i'm using an hp 83752b to generate a signal up to 20 gigahertz and then pass it to this military multiplier times six that's going to generate signals up to 120 gigahertz and there is a waveguide to coax converter and a one millimeter cable which goes to the front of the unit i think there is something a little poetic about using such an old instrument to measure such a new instrument there's a enormous gap in time and technology between these two units and i wonder if the engineers who designed this ever envision reaching this point which is really amazing the other advantage of using this is that because this is a such a high phase noise unit and it has its own imperfections and it has poor harmonic performance you will be able to capture some of those imperfections directly with the oscilloscope and examine how the multiplier actually behaves as the input signal to it increases and how it's harmonic changes so it's going to be an interesting setup and an interesting result so let's go ahead and zoom to the screen and see what we get so let's take a look at the output spectrum that this instrument produces right now i have channel one set to full band with 113 gigahertz at the full sample rate 384 000 points and 150 nanoseconds per division this allows me to compute the fft and the fft will span anywhere from zero hertz all the way to up to 128 gigahertz at the resolution bandwidth of one megahertz we can in fact look at that just to make sure the resolution movement is one megahertz there it is one megahertz resolution bandwidth and check it check the noise floor here the displayed average noise floor for this setting is around minus 80 dbm this is extraordinary for such a broadband front end for an oscilloscope and there's nothing connected to the input right now and take a look there are almost no tones at the output of this adc meaning every single harmonic of every single clock that's generated is so well filtered and so well accounted for here there is only a little bit of a signal at 64 gigahertz in the middle of the spectrum and that's from the front-end sampler very difficult to get rid of that signal but even that is sitting at around minus 76 or 75 dbm on average and perhaps in the future version the final version it might be even better than this so having said that this is not even at the highest sensitivity because we are at 50 millivolts per division if i were to reduce this all the way down to 2 millivolts per division the displayed average noise floor at the same settings is going to continue to get better and better for instance i can go down to 20 millivolt per division and you can see that the noise is already much lower even though the resolution manual is exactly the same as it was before so if you need to make a very sensitive measurement you can get noise floor much better than 86 dbm simply because you can go all the way down to 2 millivolt per division which is the limit of the hardware front end sensitivity now of course it means that this the logic signal you can capture is going to shrink as well but if you need to make sensitive measurements that's the way to do it so let's go back to where we were because we're going to do some measurements here that's going to require a larger vertical spacing there so there it is back to where we were now i want to investigate and see what happens to this multiplier as i increase input signal power to it and normally multipliers have a nominal input signal be under which they don't operate very well but i'm curious to see how it behaves as i change the input signal so right now i have it at 18 gigahertz so 18 gigahertz times 6 is 108 gigahertz that's what i expect the multiplier to produce first we're going to give it minus 10 dbm and see what happens so let's go ahead and turn the power on to the multiplier and the signal on there it is now you can see as soon as i turn the signal on there are some additional tones appearing in the fft now you don't see it at all in the vertical here because it's so small but we can see that the instrument is capturing a signal at 72 gigahertz at minus 58 dbm but 72 gigahertz is 18 times 4 it's not 18 times 6 which means that this multiplier right now has a larger times 4 output than it does at time six but even the time six can be seen right over here is a tiny little peak coming out at 108 gigahertz we're not recording it because it's below the peak level that i have defined so it's not capturing that peak there but let's go ahead and increase the signal and see how these two harmonics interact and what happens with the input signal up to the output signal as i increase that so here we go going higher and higher you can see that they're both growing and the times four is still growing we're going to continue over here let's stop here for a second and right now the two of them are almost the same amplitude the 72 gigahertz is minus 38 the 108 gigahertz signal is -41 so this multiplier is still not working very well but i expect that as i increase the input signal eventually we're going to reach a point where the multipliers input devices and the amplifiers which are tuned to produce time six are going to operate in large signal and they're going to get rid of the other harmonic that's undesired so let's go ahead and try that we're going to keep increasing it and i expect the times 4 to begin to shrink there it is you can see it is shrinking now and i'm going to go all the way to an input signal of 0 dbm let's go ahead and stop at 0 dbm there it is and check it out here's our fundamental output this is sitting at 108 gigahertz minus 12 dbm and the 72 gigahertz signal is at about -30 dbm so that gives us 18 db of rejection between the fourth and the sixth harmonic of the input signal which isn't really good but perhaps for this kind of multiplier screening off this also tells us that if your system is sensitive to a 72 gigahertz signal even though this is a wr10 waveguide if you're sensitive to this signal you're going to have to put a waveguide filter after this otherwise this is going to continue to be present in your system and the fundamental signal sitting all the way out there is of course now significantly larger and you can see a whole bunch of other harmonics here these are all the multiples of 18 as well as all the other harmonics that this old synthesizer is producing they're all mixing intermodulation products are showing up they're just all over the place now to do a meticulous test to figure out which of these is coming from what and if any of them are coming from the a2d converters of the oscilloscope you're going to have to do any a much better source is required and i'm going to save that for when we get the final version of the instrument but nonetheless we can clearly see that this instrument is going to have a very strong fourth harmonic coming out this also means that we're going to be able to capture this in the time domain and if i capture it in the time domain we are going to be able to see some double edging because of all this smart strong harmonics present in the spectrum we can actually test that let's go ahead and turn off the ffd since we're done with it there it is and let's go ahead and try and zoom in a little bit more let's keep going until we see the sinusoid and here we go there is our sinusoid you can see it very clearly this is a 108 gigahertz sinusoid and you can see double edging and triple aging and some of this because it has strong harmonics and look at how sharp the trigger is and this is because the trigger has full 113 gigahertz of bandwidth done in the digital domain in the digital signal processor and it's doing a fantastic job and you can see how the signals spread as they move away from the trigger point because of all the other harmonics that are present but the trigger is working perfectly fine now the spectrum signals that we measured traditionally you can really only do that with a spectrum analyzer and the only spectrum analyzer in the world that can give you the spectrum of this from dc to 110 is the uxa which is also from keysight so now you can do this on their oscilloscopes as well which is just madness to be able to do this kind of measurements up to these frequencies it's really impressive i also wanted to show you some primary measurements that keysight has done on this instrument and keep in mind that these are done on a prototype this instrument's not completely finished yet so these measurements are likely going to change and probably improve by the time the final instrument is released now here the instrument is set to a bandwidth of 70 gigahertz and at this bandwidth they're trying to measure the flatness of the front-end response as well as the effective number of bits and noises some of the other measurements now if you look here you can see how flat the frequency response is i mean this is within plus some minus 0.75 db or so all the way to 70 gigahertz which is a 3db bandwidth of the instrument and this is not even the final version it's very difficult to accomplish this they also measure the enum but if you look at the enop from dc all the way up to 70 gigahertz this dip you see here you have to ignore because that's cut off fighter by the dsp anyway so really the measurement that's only valid all the way from dc to 70 gigahertz the enop is just below 6 db and it's completely flat regardless of the input frequency this means that it's entirely noise limited and it's not distortion limited so that if you were to continue to increase to reduce the bandwidth of the front end the enub is going to continue to get better and better up until a certain point where distortion might kick in this is the kind of measurements that i would want to do on the final version of the instrument but to be able to get this is really quite impressive the noise we've already measured which matches these numbers now we can go all the way to 110 gigahertz so in this case 113 gigahertz and again you can see the front-end bandwidth here fairly flat and this is going to further improve once they complete the instrument is really quite impressive same with the enoch is again flat all the way up to 113 gigahertz similarly just around five and a half db which i'm sure it's going to be improved a little bit more too i'm very curious what would be the e knob let's see at one gigahertz with a one gigahertz filtered bandwidth and up to one gigahertz input frequency but i mean take a look at this is flat all the way up to 112 gigahertz completely noise limited this is really good and it promises to be able to get better and better enough as the frequency changes and because of this low noise performance of the oscilloscope and because of the good effective number of bits we get we can do measurements at a performance level never accomplished before so here's an example of a 64 gigabyte 64 coherent modulation that's being used in the scope as a receiver here and you're hitting an evm of 2.8 percent for 64 gigabytes 64 qm that's more than 600 gigabit per second equivalent rate for coherent communication now the previous best measurement was at 5.4 percent evm and this improvement is primarily due to the fact that channel to channel a jitter is less than 35 femtoseconds and that means that the constellation is preserved going through the oscilloscope and ultimately digitized and processed by the dsp is really quite amazing furthermore you can do things that could never been done before this is a 64 gigabyte 256 qm that's a terabit per second equivalent coherent modulation the vm is again 2.6 percent nobody has ever done this measurement on an oscilloscope before all right i hope you enjoyed this video there was a lot of information and i definitely really enjoyed making it i only had this scope for a couple of days so i didn't have a lot of time to do detailed experiments but then i can't wait for the final full version to be out with four channels so we can do some crazy setup and see what we can capture with it now having said that i'd love to hear what you guys think in the comments section let me know what you thought of the oscilloscope and we can discuss some of the details of its design and if you have any questions i'll try to answer them i'm sure the keysight staff would also love to answer your questions this is a wonderful accomplishment really for engineering and i think we should all celebrate that i'll see you in the comments section

Channel: The Signal Path

Views: 112,065

Rating: 4.9505453 out of 5

Keywords:

Id: DXYje2B04xE

Length: 54min 34sec (3274 seconds)

Published: Tue Sep 18 2018

Reddit Comments

[u/wasianish]

This popped up on my newsfeed, props to u/TheSignalPath for this

[u/mantrap2]

This is a pretty hardcore scope. And $$$$$$.

[u/ratn9ne]

The golden front-end PCB is an absolute microwave masterpiece, it alone looks like it could cost 50K..... or more, I think the price on the instrument is 1.3M.

[u/[deleted]]

What kind of mortgage can I take out for this? Is it FHA approved?