Author Topic: why Phase detector IC input pin reading is always the same?  (Read 1037 times)

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Offline fikaduTopic starter

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why Phase detector IC input pin reading is always the same?
« on: February 14, 2018, 01:12:34 am »
 I am software guy, don't have much idea about RF design.
These days,  I am trying to experiment on phase detector IC(AD8302). As attached figure, while trying to measure an input values at pin INPA and INPB, it always reads 4.85V. This reading is the same whether there is RF power or not. Actually, the output reading is correct as compare to phase shift on Oscilloscope. An input limitation(maximum) at those two pins is –13dbV(0.22V) as it is  described on the datasheet. Even that was why I added the voltage divider on the input side as shown in the figure. My doubt here is that, why the reading is always 4.85V and would it be safe? can input at pin INPA and INPB exceeds –13dbV(0.22V) ?

Datasheet:   http://www.analog.com/media/en/technical-documentation/data-sheets/AD8302.pdf

Thank you all
 

Offline Rerouter

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Re: why Phase detector IC input pin reading is always the same?
« Reply #1 on: February 14, 2018, 09:47:55 am »
The voltage is due to the architecture of the device, it not being there would be more concerning, now what frequencynare you feeding in, the stockncircuit expects about 100KHz and up, needing the capacitor values tweaked for lower frequencies at the cost of responsiveness
 

Offline fikaduTopic starter

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Re: why Phase detector IC input pin reading is always the same?
« Reply #2 on: February 18, 2018, 06:16:43 am »
 Thank you a lot.
I am using 13.56MHz RF power.
 


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