January 18, 2006 – Kopin Corp., Taunton, MA, has ramped to volume production of its GaAsInN heterojunction bipolar transistor (GAIN-HBT) wafers, targeted for use replacing InGaP HBT wafers for cell phone power amplifiers.

Adding varying amounts of indium and nitrogen into the GaAs wafer reduces bandgap energy for low-voltage operation and creates an internal electric field for higher speed, allowing power amplifiers to maintain their performance over greater temperature ranges and ultimately higher power efficiency. The greater band-gap difference between the transistor emitter and base layer also makes the GAIN-HBTs more reliable, according to Roger Welser, Kopin director of new product development.

Kopin and Skyworks Solutions are developing a fully integrated PCS handset power amplifier based on GAIN transistors, which operate under low-temperature and low-voltage (2.6V, the level used with other circuits), while most GaAs-HBT power amplifier ICs stop working below 2.8V reference voltage.