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HMC981LT3E to biais Variable Gain Amplifier (VGA)

Question asked by team2265 on Mar 11, 2018
Latest reply on Jun 11, 2018 by David_Wong

Hi,

 

As far as I understand, this component will regulate the current based on the R10 value positioned on Rsense.

 

Now let's say i use this HMC981 to biais a variable gain amplifier (VGA) where it has two gates voltages, vg1 (fixed value) and vg2 (that can be modify to obtain the gain).

 

What will happen if I decide to put a potentiometer on the Rsense and change the current value, will it changes only the VG1 to reach the desired current ? Or Vg1 and Vg2 ? Is there is a way to only regulate with Vg2 the current ? 

I am talking about large currents variations (let's say 100mA at nominal biasing and down to 10mA to reduce the gain).

I believe changing the Rsense value in operation will change the vg1 to regulate, which is what we want to regulate but what about wanted current variations ?

 

Do you have any solution with this component to take advantage of the gain dynamic of my amplifier by varying vg2 ?

 

Thank you in advance,

John

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