Very close. Tek always gave the formula: 0.35/BW ; it's based on the semi-mythical gaussian bandpass characteristic. If aberrations are significant, neither can be trusted.
You probably know the formula for estimating risetime when the measurement approaches the instrument limits: tr= sqrt(tmeas^2 - tinstr^2) which of course only works when you already know that the pulses are clean - which you probably can't tell with that scope.
-- Yup; a "single-channel externally-triggered complementary-output pulse generator", from Larkin's blurb.
=
Yes, assuming the probe is not a limitation. But the observed risetime is t he RMS of signal + scope risetimes.
au=
No I didn't know that. Thanks, I guess mostly I like to have minimal instrumental effects :^)
George H.
That used to be true. The high-end digital scopes that I've tested lately don't seem to have gaussian response; they seem to be tweaked for bandwidth bragging rights, and subsequently ring.
My "200 MHz" Tek DPO2024 rings a bit and has a rise time of 1.85 ns.
-- John Larkin Highland Technology, Inc jlarkin at highlandtechnology dot com http://www.highlandtechnology.com Precision electronic instrumentation Picosecond-resolution Digital Delay and Pulse generators Custom laser drivers and controllers Photonics and fiberoptic TTL data links VME thermocouple, LVDT, synchro acquisition and simulation
Fie. Analog parts on the digital board.
This should satisfy most captious critics.
VLV
It's actually more general than that--there's a Fourier transform theorem that variances add under convolution, so providing the pulse widths and rise times are defined in terms of the second moments, and there are no loading effects due to cascading the two devices, this formula works exactly.
Cheers
Phil Hobbs
-- Dr Philip C D Hobbs Principal Consultant ElectroOptical Innovations LLC Optics, Electro-optics, Photonics, Analog Electronics 160 North State Road #203 Briarcliff Manor NY 10510 USA +1 845 480 2058 hobbs at electrooptical dot net http://electrooptical.net
The low input flushes the delay chain. Cute.
-- John Larkin Highland Technology, Inc jlarkin at highlandtechnology dot com http://www.highlandtechnology.com Precision electronic instrumentation Picosecond-resolution Digital Delay and Pulse generators Custom laser drivers and controllers Photonics and fiberoptic TTL data links VME thermocouple, LVDT, synchro acquisition and simulation
es
lThat's pretty, but if the part's fast it might not meet George's min. output pulse needs. An R-C or two would fix that.
-- Cheers, James Arthur
te:
layout using that parts family. It used to be a point of advantage for a l ogic family that it was unresponsive to full logic level transitions of dur ation less than the fastest edge rates in the system. Interwiring capacitiv e coupling into a nice high impedance input converts the transition into a nice square pulse there. I think Lenin covered that one.
Sweet, I think a nice one shot is the right medicine. It looks like I'll stretch it out to ~200ns, not a big deal with 1us bins, the first time bin is ~20% 'short'. We'll document it in the manual and specs,
70% of our users will never notice.Hey, we should use the 200ns pulse as the monitor output! maybe they'll notice if it's on the 'scope.
I'm not sure why I didn't have a one-shot in to begin with. (there's been some 'vibe' that one shots are bad.(?) It all seems so obvious in retrospect.
George H.
It's so crappy, it's almost Larkinesque. The f...ing "specification" was to widen a 5ns sliver. A 5ns sliver won't even produce a sigh out of 74HC stuff. ...Jim Thompson
--
| James E.Thompson | mens |
| Analog Innovations | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| Phoenix, Arizona 85048 Skype: Contacts Only | |
| Voice:(480)460-2350 Fax: Available upon request | Brass Rat |
| E-mail Icon at http://www.analog-innovations.com | 1962 |
I love to cook with wine. Sometimes I even put it in the food.
So design something. Do you remember how?
-- John Larkin Highland Technology Inc www.highlandtechnology.com jlarkin at highlandtechnology dot com Precision electronic instrumentation Picosecond-resolution Digital Delay and Pulse generators Custom timing and laser controllers Photonics and fiberoptic TTL data links VME analog, thermocouple, LVDT, synchro, tachometer Multichannel arbitrary waveform generators
:)
Jamie
t
out it.
describes the emitter-coupled monostable. Put one together out of a pair of wide-band tansistors - BFR92 or better - with 33R up against each base, and you can cetainly get below 10nsec. Since the mechanism depends on the change of base-emitter impedance with emitter current, it isn't as easy as it might be to get a wide range of output pulse widths.
Jim Thompson could probably remember a better solution for you. The long-obsolete MC10198 ECL monostable
could just get down to 10nsec, but we used two of them when we wanted to offer long pulses as well - being able to switch in bigger capacitors put too much stray capacitance on the relevant input pin for 10nsec operation.
Something boringly obvious with a constant current ramp and a fast comparator would do the job, but - as with the MC10198, being able to switch in bigger capacitors to generate much longer pulses is probably incompatible with a 10nsec pulse width.
-- Bill Sloman, Sydney
it.
I want 10 picoseconds, not 10 ns. I already sell boxes that go down to 100 ps pulse width.
I just need another factor of 10.
-- John Larkin Highland Technology Inc www.highlandtechnology.com jlarkin at highlandtechnology dot com Precision electronic instrumentation Picosecond-resolution Digital Delay and Pulse generators Custom timing and laser controllers Photonics and fiberoptic TTL data links VME analog, thermocouple, LVDT, synchro, tachometer Multichannel arbitrary waveform generators
that
about it.
&dq... 0 psInteresting. If electromagnetic radiation propagates 20cm in 1nsec in ordinary dielectrics, 10psec is 2mm, and it's going to be a bit tricky to provide connections that don't introduce significant impedance discontinuities. Are you planning on designing stuff that surface mounts onto his printed circuit?
Since microstrip is intrinsicly dispersive, strip line might be better, and he'd have to sandwich your contribution.
Clearly a fresh field to conquer, not exactly nano-engineering, but definitely one for the tiny-minded.
-- Bill Sloman, Sydney
--- Fuck you.
I've posted enough stuff over the last fifteen years or so to have established my reputation as a designer, and I certainly don't have to dance to your tune to prove anything to anyone.
-- JF
Well? Larkin has certainly posted A LOT MORE... no matter that it's just non-functional crap >:-} ...Jim Thompson
--
| James E.Thompson | mens |
| Analog Innovations | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| Phoenix, Arizona 85048 Skype: Contacts Only | |
| Voice:(480)460-2350 Fax: Available upon request | Brass Rat |
| E-mail Icon at http://www.analog-innovations.com | 1962 |
I love to cook with wine. Sometimes I even put it in the food.
-- I think Larkin is far and away the most copious poster here of off-topic material.
Yep. Mostly narcissistic nonsense. He must forever be on stage to satisfy that BU-grade narcissism >:-} ...Jim Thompson
--
| James E.Thompson | mens |
| Analog Innovations | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| Phoenix, Arizona 85048 Skype: Contacts Only | |
| Voice:(480)460-2350 Fax: Available upon request | Brass Rat |
| E-mail Icon at http://www.analog-innovations.com | 1962 |
I love to cook with wine. Sometimes I even put it in the food.
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