Design of MMIC power amplifiers for multi-band CDMA/W-CDMA mobile terminal applications

Abstract

Two different MMIC(monolithic microwave integrated circuit) single power amplifier structures are proposed and demonstrated for multi-band mobile terminals applications. An MMIC single power amplifier with dual input(SPDI) has been devised for cellular/PCS/W-CDMA triple band applications, and an MMIC single power amplifier with single input(SPSI) has been devised for cellular/PCS dual-band application. These multi-band single power amplifiers can achieve a small chip and module size and operate with single operation voltage. Moreover, the SPSI structure can be applied for the power amplifier of single ended intelligent radio or software defined radio system. These structures have been applied to MMIC power amplifiers for mobile terminals with InGaP/GaAs Hetero-junction bipolar transistor (HBT) technology. First, this paper proposes a cellular/PCS/W-CDMA triple-band HBT MMIC power amplifier implemented with a single power amplifier dual input(SPDI) structure. The SPDI structure can make the chip size smaller because the power-stage transistors occupying large area separately for each band in the conventional multi-band circuits have been reduced to one for multi-band in common. Further, the module size reduction can be achieved by utilizing a single power supply and bias circuit. The two different bias currents for cellular and PCS/W-CDMA bands are optimized for the respective bands through a bias control circuit from a single supply voltage source. Appropriate design of the inter-stage matching networks and dual output matching networks can satisfy the triple band specifications even with the common power-stage amplifier. This two-stage power amplifier complies the triple band requirements at the same time. The MMIC has the power gain of 30dB(26dB,25dB) and maximum output power of 30dBm(29dBm,25dBm) for cellular(PCS,W-CDMA) band. The power-added efficiency (PAE) at the output power of 28dBm is 43%(39%) and the adjacent channel power ratio (ACPR) at the output...