An EL52 has differential D and clock inputs. The D input becomes the signal to be sampled and the slow feedback. The diff clock input can be the equivalent-time ramp timebase comparator.
Not bad for one 8-pin part.
-- John Larkin Highland Technology Inc www.highlandtechnology.com jlarkin at highlandtechnology dot com Precision electronic instrumentation
However, min pulse width is 400psec which is almost twice of what my goal is.
Indeed. They don't go berserk during phases where the two D inputs are close to each other and barely moving? Most of the time when I did that with logic chips everything lit up.
-- Regards, Joerg http://www.analogconsultants.com/
The real question is how fast the front end of the flipflop is. Prop delay after that doesn't matter.
Use an EP52 to go faster. SiGe.
Well, you'd have to try it.
-- John Larkin Highland Technology Inc www.highlandtechnology.com jlarkin at highlandtechnology dot com Precision electronic instrumentation
of the comparator (node OUT)
comparator slews the output to the input value. When node OUT is equal to the input signal, node OC rises.
translation circuit)
conversion.
stuff.
Well kind of sorta. Most of their use is in demodulating QAM 8 and similar signals, relatively yes/no types of stuff. Once upon a time they were the proper real thing (about 30+ years ago). They weren't nearly as fast back then either.
?-)
4GHz is impresive but it also wants a minimum pulse time, this one even says 450psec.
Yep. If there is enough time I could but it would still be dicey. Seen too many designs where folks relied on certain undocumented performance features. Then the mfg built a new foundry, moved the process over, and ... poof.
Like you I drive FETs and stuff well past their datasheet speeds but those are fairly staid processes. They are also cheap so even a lifetime purchase can be feasible. But I've seen a case where someone did that in the world of optics and suddenly a whole big product line came crashing down.
-- Regards, Joerg http://www.analogconsultants.com/
You want the HFA3101 for that. Same die.
If you capacitor-couple so one edge puts a current pulse into a gain cell (I suggested the OPA860) the sampling only lasts as long as the current pulse. The rest of the 'pulse width' is just deadtime, which (in most samplers) isn't the big concern. The OPA860 is a transconductance amplifier, output current is nil after you turn off its Iq current source. That's the 'hold' part. And current output is proportional to input voltage times Iq when the Iq source is on. That's the 'sample' part. During dead time, you need to both digitize the sampled value, and discharge the capacitor to some known level. And, reset the flip/flop.
AFAIU that will not working with the flip-flops John suggested because they are not guaranteed to function with less than 400psec. But who knows what they do inside, it might work.
Using it directly to sample the RF could be a stretch because the BW of the OTA in there is low. But it might be useful as a "post-sampler" which I'll need because of slow ADC capabilities. The off the shelf S&H chips are boringly slow. No idea why because I've built much faster ones in discrete and there was nothing that would have prevented integration into a chip.
-- Regards, Joerg http://www.analogconsultants.com/
The clock can be very wide; only the rising edge matters. The question is, what is the effective bandwidth of the latch inside?
This is too good not to try:
Sampler and timebase comparator in one chip!
-- John Larkin Highland Technology Inc www.highlandtechnology.com jlarkin at highlandtechnology dot com Precision electronic instrumentation
Is the 2 diode sampler used any more due to the delay of the resistors in this configuration or is it another 2 diode sampler you are referring to?
What would be good mathing diodes for the 4 diode samplers?
Cheers
Klaus
no idea, never had to build sampler only seen it on a schematic :)
I wonder if those low capacitance ESD array could be used?
say something like CM1230-02CP for a four diode ?
-Lasse
2-diode samplers have been done up to 200 GHz or so. They are monolithic structures with shock-line sample pulse generators. Google shock line sampler or something like that.
-- John Larkin Highland Technology Inc www.highlandtechnology.com jlarkin at highlandtechnology dot com Precision electronic instrumentation
Not just that. Also important is what it'll do in the analog range (inputs very close to each other or nearly identical).
That is very clever. Wish I could try that but the lowest I can measure in my lab here is around 500psec.
The risk is oscillation and it happened when I tried something similar, trying to log time between fast zero crossings. When they became slow or the signal dropped out the indicated power supply current suddenly jumped up, big time. The chip became smoking hot, even after I took everything except the terminators off the output. The onset was always sudden, indicating internal oscillation although we had no tools back then to verify emissions in the GHz range. Ok, this was in the days when Motorola was still Motorola but probably the innards of such ECL chips haven't changed much other than in the foundry process.
-- Regards, Joerg http://www.analogconsultants.com/
When I did my masters project we had to buy expensive quad packs, probably hand-selected by a well paid HP employee. Came in a tiny envelope. The ones they use for drugs nowaday :-)
I don't think you can buy matched quads anymore and the closest to that in performance would probably to buy a bridge quad in a single SMT package, see page 1, bottom:
They also make ring quads for RF mixers. But the purchasing department has to keep a close eye on things because distributor stock can be limited with these specialty devices.
Anything better would probably mean someone has to sit down and hand-select diodes like the higher-end manufacturers did in the old days.
-- Regards, Joerg http://www.analogconsultants.com/
You can squat in our lab, if it helps. We have digital delay generators with 1 ps resolution and sampling scopes up to 50 GHz. I'd enjoy seeing how that single-flop feedback sampler works.
ECL shouldn't get hot if it oscillates; everything is diff pairs fed by current sources. ECL gain is fairly low, so it might not oscillate at all.
I once played with teasing the D input of an ECL flop, against the clock, to see what the actual setup/hold boundary behaved like. I could move D something like 5 ps and move from solid 1 to solid 0 at Q. There seemed to be some hysteresis, a couple ps, in the setup/hold time, which was interesting.
-- John Larkin Highland Technology, Inc jlarkin att highlandtechnology dott com http://www.highlandtechnology.com
Thanks, and I'd buy beer :-)
Unfortunately I am swamped right now so a road trip of a day would be tough.
I had it jump so much that you could not touch it with a finger without letting off a scream.
Maybe the newer ones are more tame, my experiment was in the early 90s. How much capacitance do they have on the D inputs to D/ and GND?
-- Regards, Joerg http://www.analogconsultants.com/
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