Improvement in ACLR asymmetry for W-CDMA InGaP/GaAs HBT power amplifier

Asymmetry in Adjacent Channel Leakage power Ratio (ACLR) has been often observed in high power amplifiers for digital wireless communication systems such as W-CDMA. This paper describes a method for reducing the asymmetry by controlling bias circuit impedance at sub harmonics. By shortening both at 4MHz and 8MHz at the bias circuits, an 8.37-dB ACLR asymmetry could be su pressed to a 5.05-dB ACLR asymmetry, where a 10.5-dl3 3 order Inter Modulation Distortion (IMD3) asymmetry could also be successfully improved to a 1.8-dB IMD3 asymmetry.