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Topic: Agilent has oscilloscopes to 63 GHz /160GS/s. How is that possible? (Read 2860 times) previous topic - next topic

JoeN

What type of technology is used to make such a ($439,824) product?  How do you sample at that rate?  160GS/s implies some sort of clock at 160Ghz.  How is that done?  I don't understand how this can be done at any price the speeds are so otherworldly.
I have only come here seeking knowledge. Things they would not teach me of in college.

BulletMagnet83

Based on EEVblog tear-downs I've watched, I think the answer is "dark sorcery and witchcraft" :D

retrolefty

Well if it can be done, Agilent is a company that could do it. As a spin-off/de-vesture of the old HP instrumentation company they were always among or leading in the state of art of measurement teck.

Lefty

KeithRB

I had an 8 GHz scope a while back, and it is done with 8 bit flash convertors and you use multiple ones and interleave the data. I am sure they have a white paper. For example, if you have 16 convertors, they each need to sample at 10 GS/sec.

JoeN


I had an 8 GHz scope a while back, and it is done with 8 bit flash convertors and you use multiple ones and interleave the data. I am sure they have a white paper. For example, if you have 16 convertors, they each need to sample at 10 GS/sec.


Out of curiosity I have looked at TI/National, Analog, and LT's sites and I think the fastest converter that is available is TI at about 5 Gsps and that is at 7-bit.  The datasheet shows it's actually 4 ADCs embedded in one chip with some clock management.  So maybe you use 32 of those?  But how the heck do you interleave them so that they are sampling at the correct point in time?
I have only come here seeking knowledge. Things they would not teach me of in college.

KeithRB

Note that you only get 63 GHz if you are using two channels, you are limited to "only" 33 GHz with all 4, so they are clearly interleaving multiple samplers.

CrossRoads

Designing & building electrical circuits for over 25 years.  Screw Shield for Mega/Due/Uno,  Bobuino with ATMega1284P, & other '328P & '1284P creations & offerings at  my website.

JoeN


Need to use something faster than an Arduino 8)


Nothing a little liquid nitrogen and a faster crystal can't fix.    8)

I realize I should have posted these links:

First thing I buy if I win the Powerball:

http://www.home.agilent.com/en/pd-2108888-pn-DSAX96204Q/infiniium-high-performance-oscilloscope-63-ghz?nid=-33202.1010838&cc=US&lc=eng

TI's obscenely fast converter:

http://www.ti.com/product/lm97600

I have only come here seeking knowledge. Things they would not teach me of in college.

SirNickity

Even if you can sample that fast, how do you put test leads on a circuit that is moving at a rate that necessitates that kind of speed?  Seems like the capacitance of any test lead would wreck it.  Crazy stuff.

JoeN


Even if you can sample that fast, how do you put test leads on a circuit that is moving at a rate that necessitates that kind of speed?  Seems like the capacitance of any test lead would wreck it.  Crazy stuff.


I think the answer is "active probes" (MSRP about $8,000 each for this speed, but you get a set with the scope), whatever that is.  Because I can repeat what Agilent says doesn't mean I understand it.
I have only come here seeking knowledge. Things they would not teach me of in college.


Papa G



I had an 8 GHz scope a while back, and it is done with 8 bit flash convertors and you use multiple ones and interleave the data. I am sure they have a white paper. For example, if you have 16 convertors, they each need to sample at 10 GS/sec.


Out of curiosity I have looked at TI/National, Analog, and LT's sites and I think the fastest converter that is available is TI at about 5 Gsps and that is at 7-bit.  The datasheet shows it's actually 4 ADCs embedded in one chip with some clock management.  So maybe you use 32 of those?  But how the heck do you interleave them so that they are sampling at the correct point in time?


HP/Agilent were never afraid to design their own hybrid chips so there is no telling how they are doing it. They used to publish a nice Journal that had articles on their technology but I can't find that Agilent do that.

KeithRB

There is a white paper on this scope which describes a 10 ns clock with really clean edges - sub-sub 1 ns risetime.

oric_dan

Quote
Need to use something faster than an Arduino

I'm not sure if this is what HP uses, but besides using multiple interleaved ADCs, there
is a technique called "equivalent time sampling" that can be used if you have a stable
trigger capability and a **repetitive** signal.

Basically, what you do is trigger at the same point in the repetitive waveform multiple
times, up to 20 or so, and with each successive trigger you introduce an increasing
time-delay on when the ADC sampling is started. Then, you reconstruct the original
repetitive waveform by re-ordering the samples from memory to the screen. It's not
difficult.

Some years ago, I did this using a 20-Mhz PIC, which has a max sampling rate of about
50-Ksps, which is normally good for sampling about a 5 Khz sinewave, if you want to
display it [for good display, the signal must be much slower than the Nyquist frequency,
eg about 10 samples per period].

With ETS on the PIC, I was able to get an equivalent sampling rate of 1-Msps. With this
I was able to resolve a 50-Khz sinewave with very good fidelity. Even better, when using
an FFT spectral display on the samples, I was able to follow an aliased sinewave all the way
to about 250-Khz, as I recall. It really is magic, :-).

pito

You can make a 100GSample/sec oscilloscope with arduino as well:
1. sync the signal at point A
2. take a S/H sample at t=A+10ps, ADC and  store data (d1)
3. sync the signal at point A
4. take a S/H sample at t=A+11ps, ADC and  store data (d2)
5. sync the signal at point A
6. take a S/H sample at t=A+12ps, ADC and  store data (d3)
etc..
after ie. 256 such loops you'll get d1..d256 from t=10ps to t=266ps with 1ps resolution..
:)
PS: as described above by oric-dan in detail :)

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