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2 quick & simple questions regarding AD8302 phase measurement

Question asked by gr8andy on Jun 29, 2014
Latest reply on Jul 7, 2014 by jdobler

Hi

I have 2 quick & simple questions regarding AD8302 phase measurement.

 

1. I  have a quick follow up question regarding AD8302 I saw in the FAQ section. It is pasted below. My question is: What is the output phase voltage of AD8302 when one of the input signal is smaller than -60dBm? Will the phase output voltage still be around 0.9V or will it just oscillate randomly between 0 to 1.8V?

thanks

Andy

 

Q.

What is the output voltage of the AD8302 gain/phase detector when there are no signals present on the inputs?

 

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A.

With no input signal, the AD8302 compares the noise on the two inputs.  The noise on the input is generally the same level, so the magnitude output is approximately 0.9V.  Due to an internal 90 deg phase shift, the Phase output is also approximately 0.9V.


2. In order for AD8302 to make a phase measurement between 2 identical periodic signals, does the signals have to be sine waves? ie can they be square waves or any other arbitrary periodic waveforms? If yes, can the duty cycle of the waveform be very low? ie, can they be square waves with very narrow pulse width (ie low duty cycle such as 1%)?

 

thanks

Andy

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