How to measure the peak of a rectified pulse without sample and hold?

[amirbaragh]

Hi
i want to measure the peak of a rectified pulse signal.one simple way is to use sample and hold.but here i have a signal in x band(high frequency) with duty cycle about 10ns.so i cant use sample and hold.please help me!

 

[BigBoss]

Re: pulse peak measurement

Gigatronics and Agilent manufacture very accurate and cost effective Peak Power Detectors and Power Meters for pulsed RF signals.
All you should to choose a appropriate Power Detector and Power Meter regarding to your frequency and Modulation Scheme.

 

[DeboraHarry]

Re: pulse peak measurement

Hi
i want to measure the peak of a rectified pulse signal.one simple way is to use sample and hold.but here i have a signal in x band(high frequency) with duty cycle about 10ns.so i cant use sample and hold.please help me!

There are some fast scopes. I used to use an old Tektronix which had a head with a risetime of 25 ps. That was probably around 20 years old, but I'm not sure what is state of the art now.

How about mixing it with a signal close in frequency, filtering out the sum frequency, and looking at the difference frequency on a conventional scope?

 

[amirbaragh]

Re: pulse peak measurement

Hi
Its a good way that i have considered it as the final way.but now i have choosed the ic ltc5564 to rectify my input and want to measure the peak of the output.note that my input is a pulse modulated signal.

 

[amirbaragh]

Re: pulse peak measurement

any help?!
indeed i need a technique to measure the peak of a pulse with mentioned property!

 

[FvM]

You didn't gave much specifications, except for unvalidated assumptions about unsuitable methods. I don't hear yet a clear question to be answered.

If you e.g. feed the ic ltc5564 output to a fast ADC, you'll measure it.

 

[amirbaragh]

i know ADC is suitable,but here the trigger of my pulses are not the same because of wide input frequency range that is 600MHz to 15GHz.also note that the duty cycle of RF input is very small.
i give the RF signal to the input of the IC(LTC5564) and at the output i have a pulse.i want to measure it.i decide to use it in a power sensor!
is that enough?!!
tanx!

 

[FvM]

is that enough?!!

No. You have already mentioned a pulse width of 10 ns, but what is the repetition rate? Depending it, you would want to implement either a simple peak detector with decay time constant or a peak-and-hold with explicite reset function.

 

[biff44]

I agree, the repitition rate is critical. If you have a 10 nS pulse that repeats at a 1 MHz rate, that is very easy to measure with a current steering diode and some R-C filtering. If you have a one time pulse, that is very hard to measure.