20-40GHz Variable Gain Amplifier

CHA2097a

Ref. : DSCHA20978021-21 Jan 08

7/8

Specifications subject to change without notice

Route Départementale 128 , B.P.46 - 91401 ORSAY Cedex - FRANCE

Tel.: +33 (0)1 69 33 03 08 - Fax : +33 (0)1 69 33 03 09

Typical Bias Tuning

The circuit schematic is given below:

Attenuator

IN

OUT

Vd2,3

Vg 3

Vg1

Vd1

Vg 2

Vctrl

For gain control operation, the three drain biases are connected altogether. In a same way, all the gate

biases are connected together at the same power supply, tuned to drive a small signal operating

current of 140mA. A separate access to the gate voltages of each stage (Vg1, 2, 3) is provided for fine

tuning of the stages regarding the application.

An additional pad is provided (Vctrl) to control the gain of the circuit, driving two cold transistors in

attenuator arrangement.