A method of measuring base and emitter resistances of AlGaAs/GaAs HBTs

Abstract

The author describes a method of determining the base and emitter resistances of AlGaAs/GaAs heterojunction bipolar transistors (HBTs) at a given bias from the S-parameter measurements at a single frequency. The base resistance values agree closely with the calculated values based on layout and sheet resistance considerations. The emitter resistance values agree with those obtained by the open collector method. The method is simple and elegant and can be applied to other bipolar devices as well. No special structures or additional measurements are required for this method.<>