David Steven Ripley

A single chip HBT power amplifier with integrated power control

The GSM power amplifier market continues to drive towards low cost and small size, but remains reluctant to compromise on performance. Current generation PA products utilize InGaP HBT to deliver RF performance and integrate bias and control on a supporting silicon die. This approach is common amongst many PA manufacturers with the exception of CMOS PA [1] solutions. This paper describes a solution using an HBT BiFET [2] technology to integrate both the precision control function and power amplifier onto a common die. The resulting solution opens opportunity for industry leading size and performance at no additional cost or RF performance penalty.

Polar loop transmitter for GSM/GPRS/EDGE

An EDGE transmitter using a nonlinear GSM type PA is presented. It is based on a polar loop architecture that employs separate feedback control of the amplitude and the phase of the output signal. With this approach, the problems with AM-to-PM as well as AM-to-AM of the nonlinear PA are essentially eliminated. There is no mode change between GMSK and EDGE, and the transmitter operates seamlessly in multi-slot EGPRS. The polar modulation transmitter meets all the GSM type approval requirements for both EDGE and GMSK in the quad band (850/900/1800/1900 MHz). It is part of an RF subsystem which is in production.

Envelope Tracking power amplifier optimization for mobile applications

Envelope Tracking (ET) power amplifiers (PA) have been developed for next generation mobile handsets and tablets to improve efficiency. The ET PA provides improved system efficiency at the highest output power levels but does require performance trade-offs which must be considered. This paper will discuss the ET system performance, compare PA technologies and will provide some of the system performance tradeoffs when implementing the ET PA.