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Author Topic: Pulse generator 150ps 1Vpp  (Read 5033 times)

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Offline luky315

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Pulse generator 150ps 1Vpp
« on: July 24, 2012, 07:39:52 PM »
I made a Pulse generator with a pulse width of about 150ps and an Amplitude of approximately 1Vpp. It uses the Step-Recovery Effect of a HF-npn-Transistor and a shorted-out Stub to shape the pulse.







Unfortunately (for you) the documentation is in german (https://engineeringarts.wordpress.com/2012/07/24/pulsgenerator-150ps-1vpp/), but I try to answer all questions.
« Last Edit: July 25, 2012, 01:36:13 AM by luky315 »
 

Offline Chipset

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Re: Pulse generator 150ps 1Vpp
« Reply #1 on: July 24, 2012, 10:07:23 PM »
Send one to dave so he can test it with his 13ghz scope.
 

Offline luky315

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Re: Pulse generator 150ps 1Vpp
« Reply #2 on: July 24, 2012, 10:32:04 PM »
I have only one handmade Prototype.
The measurement is made with a LeCroy WAVEMASTER 8620A (20Gs/s) and verrified with an Agilent 86100B (Agilent 86118A 70 GHz Remote Sampling Module), so there is no need to use a slow13GHz Scope ;)
 

Offline Lukas

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Re: Pulse generator 150ps 1Vpp
« Reply #3 on: July 24, 2012, 11:45:09 PM »
Can you post the documentation anyway, there are some German members, as well.
 

Offline Chipset

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Re: Pulse generator 150ps 1Vpp
« Reply #4 on: July 25, 2012, 12:15:47 AM »
It being in german isn't really a problem, pasting it in google translate usually yields readable enough results.
 

Offline Time

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Re: Pulse generator 150ps 1Vpp
« Reply #5 on: July 25, 2012, 12:58:35 AM »
Ugly board, beautiful pulse!
-Time
 

Offline robrenz

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Re: Pulse generator 150ps 1Vpp
« Reply #6 on: July 25, 2012, 01:39:10 AM »
Doesn't a pulse for this type of measurement need at least a short section reasonably steady state voltage before it drops?

Offline ejeffrey

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Re: Pulse generator 150ps 1Vpp
« Reply #7 on: July 25, 2012, 01:50:49 AM »
I can't speak for everyone else, but when I use a pulse generator I typically want either the shortest pulse possible or the fastest step possible holding the 'high' value for at least 10s of nanoseconds.  I can't think of a time I have wanted a pulse with 250 ps rise and fall times but a 1.5 ns hold time at the top.
 

Offline luky315

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Re: Pulse generator 150ps 1Vpp
« Reply #8 on: July 25, 2012, 01:55:26 AM »
This Pulse Generator ist used for Cable testing, not for BW-measurements.
But can also be used to test the BW of a scope if you use the Cursors and not the internal
Risetime-measurement-function.
 

Offline robrenz

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Re: Pulse generator 150ps 1Vpp
« Reply #9 on: July 25, 2012, 02:08:18 AM »
This Pulse Generator ist used for Cable testing, not for BW-measurements.
But can also be used to test the BW of a scope if you use the Cursors and not the internal
Risetime-measurement-function.

That makes sense. Thanks

Offline T4P

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Re: Pulse generator 150ps 1Vpp
« Reply #10 on: July 25, 2012, 06:10:03 AM »


13GHz slow? And what's that POS i see before me anyway  :) (LeCrap)
http://the4thpin.comeze.com <-- Rants and Reviews! sorry my english  :palm:
 

Offline Mechatrommer

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Re: Pulse generator 150ps 1Vpp
« Reply #11 on: July 25, 2012, 06:13:44 AM »
But can also be used to test the BW of a scope if you use the Cursors and not the internal
how can be sure if the lower BW scope unable to reach full 1Vpp?
Ugly board
shrug... i wonder how he did the vias stitching and ensure connectivity... neat.
Quote
13GHz slow?
its relativity ;)
if something can select, how cant it be intelligent? if something is intelligent, how cant it exist?
 

Offline robrenz

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Re: Pulse generator 150ps 1Vpp
« Reply #12 on: July 25, 2012, 06:16:06 AM »
i wonder how he did the vias stitching and ensure connectivity... neat.


Looks like copper eyelets to me.

Offline luky315

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Re: Pulse generator 150ps 1Vpp
« Reply #13 on: July 25, 2012, 06:37:05 AM »
The Vias are made with a Bungard "Bel Favorit" hand press. They are small (d=0,8mm) copper rivets.
 

Offline robrenz

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Re: Pulse generator 150ps 1Vpp
« Reply #14 on: August 03, 2012, 09:24:32 PM »
This Pulse Generator ist used for Cable testing, not for BW-measurements.
But can also be used to test the BW of a scope if you use the Cursors and not the internal
Risetime-measurement-function.

That makes sense. Thanks

Quote
I thought about it some more and now I disagree. Here is how I am trying to wrap my head around this.
1. for BW testing we are using a relatively instantaneous risetime to measure how high a harmonic content the scope can digest.  A risetime of zero would contain all the odd harmonics to infinity.
2. If you have a pulse generator that outputs a pulse with no defined flat at the top and you calibrate it's risetime by measuring it on a hypothetical scope that has infinite BW. You could use it because you know the actual risetime or the dV/dT.
3. When you use your less than perfect scope to measure a "zero risetime" pulse with a flat top, the bandwidth required to measure the peak voltage at the steady state drops to a level any scope can handle. That makes sure the voltage used in your dV/dT has relevance or is as accurate as your scopes vertical.
4. When you use your less than perfect scope to measure a "zero risetime" pulse without a flat top, the bandwidth required to accurately measure the voltage on either side of the peak remains infinite. That means the voltage shown and used in your dV/dT has no relevance as it will be much lower than that shown on the infinite bandwidth scope.
5. Even with the flat top you still need to know the actual risetime of the pulse to add to your scopes measured risetime to do an accurate BW assessment.

This is pure opinion and needs to be verified by those who are more knowledgeable. ;D
« Last Edit: August 03, 2012, 09:42:08 PM by robrenz »
 


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