The linear operation of a HBT with a GaAs/InGaP composite collector structure is demonstrated. The composite collector structure allows for a thin collector design that is suitable for the linear operation of a HBT without critical degradation of the breakdown voltage. The load pull measurements under a 1.95 GHz WCDMA signal have shown that a composite-collector HBT with a 400-nm thick collector layer operates with power-added-efficiency (PAE) as high as 53% at VCE = 3.5 V as a result of improved distortion characteristics. Despite the thin collector design, collector-emitter breakdown voltage of 11 V was achieved even at current density of 10 kA/cm2. The composite-collector HBT has even greater advantage for future low voltage (< 3 V) applications where maintaining PAE and linearity becomes one of the critical issues.

A new high ruggedness Power MOSFET structure with a planar oxide self align p+ implant structure is proposed and discussed. We compare the proposed self-align process with the conventional p+ MASK process and contact p+ implant process. It is shown that the self align implant structure with a wide p+ area can reduce the parasitic BJT effect and, therefore, improve the device's avalanche energy capability, which is required for inductive load circuits. Based on the unclamped inductive load switching measurement results, the proposed device avalanche energy with self align p+ implant process is improved about 355% as compared to the traditional one.