Output Power Control in Class-E Power Amplifiers

A technique is presented to facilitate power control of cascode class-E power amplifiers (PAs). It is shown that by controlling the signal applied to the gate of the cascode transistor, the transmit power is changed. The main advantage of the proposed technique is a high 36 dB output power control range (PCR) compared to 20 dB for the traditional approach. This fulfills the requirements of the GSM standard on the PCR at all power levels and all frequency bands (for GMSK modulation). The concept of the cascode power control of class-E RF PA operating at 2.2 GHz with 18 dBm output power was implemented in a 0.18 ¿m CMOS technology, and the performance has been verified by measurements. The PA has been tested by a single tone, and by a GMSK modulated input signal.