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Topic: Agilent has oscilloscopes to 63 GHz /160GS/s. How is that possible? (Read 2 times) previous topic - next topic


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.


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


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

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, :-).


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)
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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