Peak Power Detector Circuit - RF Cafe Forums
Post subject: Peak Power Detector Circuit Posted: Sun
May 14, 2006 10:44 pm
Joined: Mon Apr
10, 2006 12:43 pm
Good day. I am looking for information
on peak power detectors.
It is my understanding that what
makes a peak detector work is more of a timing issue then anything
else. For example the burst of RF energy that needs to be measured
is about 5 mS in length with a 100 mS off time between bursts. Now
the detector does not have a long time constant (the response time
of the diode is on the order of 100 nS). So the ADC needs a trigger
to begin conversion when there is an RF signal present.
Is this the basic premise of a peak power detector? Any additional
information would be appreciated.
Post subject: Peak power detectorPosted:
Tue May 16, 2006 6:38 pm
Feb 22, 2006 3:51 pm
There are some
assumptions in your posting that I'd like to clarify.
The output of the peak detector must be a digital word, with enough
bits (whatever that is).
2. The signal you're working with is
a pulse, or pulse-like.
3. The timing of the presentation of
the ADC output bits isn't particularly important (in other words,
the signal's amplitude is slowly varying, if it changes at all).
4. You're interested in pulse-to-pulse variation (perhaps?)
Peak power detectors are often implemented in analog circuitry,
where time constants, pulse widths, pulse repetition rates, etc
have a distinct bearing on circuit designs.
Post subject: Peak power
detectorPosted: Thu May 18, 2006 10:27 am
Joined: Mon Apr 10, 2006 12:43 pm
day Fred. Thank you for your response.
For right now, I
am looking for some general information about how to design a peak
Let me restate my position to help clarify
what I am talking about.
I will have an RF signal that is
pulsed. I need to be able to measure the power for each pulse. I
have made a couple of assumptions that might be my problems
1) The response time of the detector is fast
enough (for example 5 uS) and the pulse width is sufficient large
(5 mS) so that there is no problem with the detector responding
to the signal.
2) The output of the peak detector needs
to go to an embedded processor so I need an analog-to-digital convertor.
3) The ADC I am using is fast enough (conversion time of
5 to 10 uS) that I do not need to worry about a sample & hold
Based on these assumptions, it is my understanding
that I would need to somehow trigger the ADC at the correct time
to get an accurate power reading.
Are my assumptions valid?
Fred - if you have some additonal information about designing
peak detectors (websites, books, magazines, etc) I would very much
appreciate any information you can provide.
Thank you for
your time and help.
Post subject: Posted: Sat May 20, 2006 4:37 am
Joined: Sun May 14, 2006 8:53 pm
Take a look at Analog Devices' website (RMS detectors
and log-amps). The following linkcontains very good documentation.