A 20-mA quiescent current two-stage W-CDMA power amplifier using anti-phase intermodulation distortion

This paper explains how the adjacent-channel-leakage-power ratio (ACLR) of power amplifiers (PAs) can be reduced by using gain-expansion amplifiers in tandem and generating anti-phase intermodulation distortion (IMD) in the driver stage to cancel the IMD in the output stage. The power-added-efficiency (PAE) can thus be increased by using near-class-B-biased driver- and output-stage amplifiers, which inherently have gain-expansion characteristics and high PAE at low output power as well as at maximum output power. At a supply of 3.5 V and an output power of 27.1 dBm, the fabricated PA with a quiescent current of only 19.8 mA exhibited a PAE of 44%, a gain of 25.2 dB, and an ACLR of less than -38.0 dBc. This is state-of-the-art performance for a two-stage W-CDMA PA with an extremely low quiescent current.