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Idea for Super Peak Detector

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Mechatrommer:
Anyone have an idea on how to make a 100MHz signal peak detector?

Simon:
err what exactly do you mean by peak detector ? does it have to pick up if the signal goes over a certain threshold or does it just have to pickup the highest peak yet to be recorded ?

ejeffrey:
Depends on what you need.  The simplest way is also super-fast, and that is to use a diode plus a capacitor.  The peak voltage is one diode drop greater than the voltage on the capacitor.  Buffer the output with an op-amp and you could be done.  The op-amp can be slow but should have a FET input.  You can use a voltage adder with a second matched diode reference to add back the diode drop to help compensate for the temperature coefficient, but it won't be perfect.

The standard precision peak detector wraps an op-amp around the diode to eliminate the voltage drop.  However, the direct approach is very slow because the op-amp has to come out of saturation.

There are a number of tricks to improve the situation.  Horowitz and Hill has a great discussion of peak detectors.  The parts named are a bit dated but the techniques are still fine -- just have a look at what is available.

johnmx:
http://www.analog.com/static/imported-files/data_sheets/ADL5511.pdf

http://www.analog.com/static/imported-files/data_sheets/AD8312.pdf

http://www.analog.com/static/imported-files/tech_articles/354831766LogAmpPuls.pdf

Measurement and Control of RF Power by Eamon Nash, Analog Devices, Inc.:
Part I: http://www.analog.com/static/imported-files/tech_articles/561216689RF_Power_Meas_Part_I.pdf
Part II: http://www.analog.com/static/imported-files/tech_articles/530790443RF_Power_Meas_Part_II.pdf
Part III: http://www.analog.com/static/imported-files/tech_articles/153166529RF_Power_Meas_Part_III.pdf

Is this what you are looking for?

Kiriakos-GR:

--- Quote from: Mechatrommer on May 29, 2011, 08:04:47 pm ---Anyone have an idea on how to make a 100MHz signal peak detector?


--- End quote ---

If we talk about FM Band and radio signals , yes I have some ideas ..

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