CHA2094b

36-40GHz Low Noise Amplifier

Ref. : DSCHA20949312 – 08-Nov.-99

6/8

Specifications subject to change without notice

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Typical Bias Tuning for Low Noise Operation

The circuit schematic is given below :

IN

OUT

Vd

Vg 1,2

Vg 3

100

100

50

For low noise operation, a separate access to the gate voltages of the two first stages ( Vgs1&2 ), and

of the output stage ( Vgs3 ) is provided.

Nominal bias for low noise operation is obtained for a typical current of 20 mA for the output stage

and 15 mA for each of the two first stages ( 50 mA for the amplifier ).

The first step to bias the amplifier is to tune the Vgs1&2 = -1V, and Vgs3 to drive 20 mA for the full

amplifier. Then Vgs1&2 is reduced to obtain 50 mA of current through the amplifier.

A fine tuning of the noise figure may be obtained by modifying the Vgs1&2 bias voltage, but keeping

the previous value for Vgs3.