Small-signal gain performance of the permeable base transistor at EHF

The small-signal amplifier performance at 40.5 GHz is reported for a GaAs permeable base transistor (PBT) having a base grating of 3200-Å periodicity and 1-mm periphery. The device was embedded in a microstrip circuit with appropriate matching networks and biased for optimal small-signal gain with Vbe= 0.2 V, Vce= 2.0 V, and Ice= 59 mA. The prototype amplifier achieved 11 dB of stable gain at 40.5 GHz. The circuit design was facilitated by the moderate impedance levels and highly unilateral nature of the PBT.