External clock for Analog to Digital Converter

Thread view:

Enable EMail Alerts

Start New Thread

Thread rating:

Bilal Amin - 27 Feb 2007 04:08 GMT

Hi Everyone,
I am working on Jitter in Analog to Digital Converters(ADCs). I am
trying to setup an experiment to see the effects of jitter in real
time ADCs. I have an ADC evalutaion board with external clock input
for sampling (i.e Sampling clock).
Now I want to produce a self created jittery signal to see the effects
of jitter in ADC. Can anyone out there have any idea(s) how I can
produce a real time clock signal with "variable jitter" for the input
of external clock? Producing a simple clock signal (i.e. without
jitter) is straight forward with the help of any signal generator but
a clock signal with "variable jitter" is a problem.

Thanks for your help.

Cheers

Bilal

Reply to this Message

Bob Masta - 27 Feb 2007 15:16 GMT

>Hi Everyone,
>I am working on Jitter in Analog to Digital Converters(ADCs). I am
[quoted text clipped - 7 lines]
>jitter) is straight forward with the help of any signal generator but
>a clock signal with "variable jitter" is a problem.

This may be a whole lot easier than you think, depending
on how much jitter you need. If you simply add the good
clock signal and some other modulating signal through a
simple resistive mixer into the input of a logic gate, the
modulating signal will bias the clock to hit the gate threshold
earlier or later than otherwise. Works best if the clock
has slow edges, which you might want to encourage
by a bit of capacitance at the gate input.

If you want a modulating source with plenty of
options (uniform white, pink, gaussian, band-limited noise,
standard waves, arbitrary waveforms, AM, FM, bursts,
sweeps, etc) you can use the sound card signal generator
in my Daqarta package. (Daqarta is shareware, but the
signal generator keeps working after the trial period so
that part is effectively freeware.)

Best regards,

Bob Masta

D A Q A R T A
Data AcQuisition And Real-Time Analysis
www.daqarta.com
Scope, Spectrum, Spectrogram, Signal Generator
Science with your sound card!

Reply to this Message

Electronics Forum / Basics / February 2007

External clock for Analog to Digital Converter