A novel non-destructive method for assessing the thermal resistance of power GaAs RF-MMIC amplifiers

Thermal resistance measurements on MMIC amplifier modules are demonstrated where the present capacitive biasing network rendered the application of classical methods relying on the gate forward voltage characteristics not feasible. It has been found that employing the drain current as a temperature sensitive measurement parameter is much less sensitive to switching transients as only voltage sources are applied. Another important benefit of the drain current method is that untypical operating conditions and possible gate damage are avoided. The method has been applied to flight modules for satellite X-band amplifiers, where no modification of the final devices for measurement purposes could be tolerated.