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ADF4355-2 Rset

Question asked by rfwishes on Nov 26, 2015
Latest reply on Dec 2, 2015 by rfwishes

Hi All,

 

I'm working with your Evaluationboard ADF4355-1, the ADF4355 is mounted.

RFoutA is 500MHz, VCO out is 4000MHz, Vtune = 2.557V.

The output RFoutA is ok, Phase Noise is ok.

Changing the Charge Pump Current I see the changes in the Phase Noise.

But I can't measure any bias at Pin22, Rset. I have removed the resistor (4k7) and the Phase Noise was the same (datasheet: Rset: Bias Current Resistor. Connecting a resistor between this pin and gnd sets the charge pump output current).

In earlier times I have used the ADF4350. Here I could measure the bias voltage 0.5V with Rset = 4k7. What is the mistake?

Many thanks for your efforts.

 

Best regards

 

Hans

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