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Pulse Shift Problem Using Detector and Comparator

Question asked by ahm@ on Jun 30, 2015
Latest reply on Jul 7, 2015 by ahm@

Hi All,

 

I wanted to set up a circuit similar to AD8318 datasheet page 18, pictures 39-40.

For this circuit I used ADL5519 as RF detector and ADCMP573 as a comparator. my main goal is to detect a pulsed signal with PRI = 100us, PW=400ns at nearly 4 GHz. we have changing RF input power level in front of ADL5519. So that at measurement mode output pulse of ADL5519  shifts. (Let's say according to 0 dBm input power, -50 dBm input powered output is shifting nearly 5ns ) that was measured triggering oscilloscope with signal source.

Since output magnitude of ADL5519 changes (AD8318 datasheet page 18, pictures 40), I wanted to convert to constant pulse shape with ADCMP573. Although ADCMP573 says overdrive voltage makes "ps" delay, my total pulse shift became about 7 ns.

 

I want to achieve constant pulse shift due to change of input RF power level. And pulse shifting is critical for me. Is it possible to make it with that cascaded circuit or am I missing something? what do you suggest for constant pulse shift due to change of input RF power?

 

ps. I also tried HMC602LP4 as a detector and ADCMP601BKSZ as a comparator resulting same result.

 

regards,

Ahmet

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