A GSM/EDGE Dual-Mode, Triple-Band InGaP HBT MMIC Power Amplifier Module

Abstract

This paper describes a 3.5V operation InGaP HBT MMIC power amplifier module for use in GSM/EDGE dual-mode, 900/1800/1900 MHz triple band handset applications. Conventional GSM amplifiers have a high linear gain of 40 dB or more to realize efficiency operation in large gain compression state exceeding at least 5 dB. On the other hand, an EDGE amplifier needs a linear operation to prevent signal distortion. This means that a high linear gain amplifier cannot be applied to the EDGE amplifier, because the high gain leads to the high noise power in the receive band (Rx-noise). In order to solve this problem, we have changed the linear gain of the amplifier between GSM and EDGE mode. In EDGE mode, the stage number of the amplifier changes from three to two. To reduce a high gain, the first stage transistors in the amplifier is bypassed through the diode switches. This newly proposed bypass circuit enables a high gain in GSM mode and a low gain in EDGE, thus allowing the amplifier to operate with high efficiency in both modes while satisfying the Rx-noise specification. In conclusion, with diode switches and a band select switch built on the MMIC, the module delivers a P out of 35.5 dBm and a PAE of about 50% for GSM900, a 33.4 dBm P out and a 45% PAE for GSM1800/1900. While satisfying an error vector magnitude (EVM) of less than 4% and a receive-band noise power of less than -85dBm/100kHz, the module also delivers a 29.5 dBm P out and a PAE of over 25% for EDGE900, a 28.5 dBm P our and a PAE of over 25% for EDGE 1800/1900.