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HMC980 bias controller used with HMC608

Question asked by AStofberg on Jul 25, 2018
Latest reply on Jul 25, 2018 by David_Wong

I am using the HMC980 bias controller with the HMC608 amplifier.

 

The input power to the amplifier is 3 dBm.

 

The bias conditions are: Rset=510 ohm (Idrain=300mA) delivering to the amplifier VDrain=4.8V and VG= -3.2V.

 

We are using the amplifier in an FMCW application. The output of the amplifier appears to oscillate at particular frequencies over the sweep (9.5 - 9.7 GHz). When we lower the drain current (Rset=580ohm), the oscillation goes away. I don't know if the issue is related to the biasing IC or the amplifier.

 

At the moment I am suspecting that the amplifier is dissipating too much power and that causes some nonlinear behaviour (refer to power dissipation figure on page 3 of datasheet).

 

Any advice regarding this problem will be appreciated.

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