ADS

[Leiser]

Hi,

I am simulating an AGC circuit with ADS. I have modelled the pin diode as a resistor whose value depends on a variable.

The value of the resistor depends on the output voltage of a op-amp, set as a comparator.

I am having some problems when relating that variable to the op-amp output voltage, so I can simulate the close loop. Does anyone know how to set a variable the current or voltage of a part of the circuit?

thanks

 

[biff44]

a simple control circuit for a single PIN diode attenuator has the pin diode, a bias resistor in series (like 3 K), and then the voltage input. You need the resistor because a good deal of the attenuation range is in the <100 uA PIN current range, and with just a voltage source attached you blow right thru that range to the mA sort of values.

http://www.MaguffinMicrowave.com

Maguffin Microwave wireless design consulting

 

[Leiser]

Correct, but I do not have the pin diode model for ADS and I am modelling it as a R(I). The problem is that I don´t know how relate I to the op-amp output.

 

[zappedagain]

How about using an ideal diode in a bias-tee setup?

John D

 

[Leiser]

Thanks zappedagain,

it really worked and I got my first closed-loop traces.

Great!