A 2-20GHz Gaas MESFET Variable Attenuator using a Single Positive External Drive Voltage

A GaAs MESFET monolithic variable attenuator has been developed covering 2-20GHz bandwidth. A novel DC biasing and control scheme, by applying control voltage to the gate as well as the drain/source nodes of the MESFETs, allows the biasing and control of the IC through a single positive external voltage source combined with a variable voltage divider. The attenuation is variable from 2.4dB to 14.0dB, at 20GHz. The attenuation flatness versus frequency is within +-0.5dB, and the input and output VSWRs are less than 2:1, over the entire frequency and control range.