High linear HBT MMIC power amplifier with partial RF coupling to bias circuit for W-CDMA portable application

This paper proposes a high linearity two-stage InGaP/GaAs heterojunction bipolar transistor (HBT) power amplifier monolithic microwave integrated circuit (MMIC), using a new on-chip linearizer, for 1.95 GHz wide-band code division multiple-access (W-CDMA) systems. The linearizer consists of the base-emitter junction diode of the bias transistor and the RF coupling capacitor. The proposed linearizer has a remarkably improved gain compression of 18 dB and phase distortion of 20°, and has negligibly little insertion power loss, and more importantly it requires no additional die area and no additional DC consumption. The HBT MMIC power amplifier, with the integrated linearizer, exhibits a maximum output power (P_out) of 30.5 dBm, a power gain of 25 dB, a power added efficiency (PAE) of 51%, at the maximum output power, under an operation voltage of 3.4 V, and adjacent channel power ratio (ACPR) of -56 dBc at P_out of 27 dBm.