A compact network for eliminating parametric oscillations in high power MMIC amplifiers

High power pHEMT (and HBT) power amplifiers frequently have oscillations that occur only when the amplifier is driven near compression; under small signal conditions, oscillations are not present. We have developed a compact RC network that effectively eliminates drive dependent subharmonic and spurious oscillations in pHEMT power amplifiers. The circuit is very compact and can be incorporated in existing MMIC power amplifier designs with little or no additional tuning to the circuit.