A Novel Power Amplifier Linearization Method for Handset Applications

A new circuit concept to improve the maximum linear output power of a Universal Mobile Telecommunication System (UMTS) power amplifier (PA) is introduced in this paper. The proposed circuit consists of an analog pre distorter (APD) integrated at the input of a class B amplifier. The proposed APD extends the maximum linear output power of the PA to 28dBm with corresponding power added efficiency (PAE) of 52.3%. Simulation result shows that at 1.95GHz, PA has a worst case adjacent channel leakage ratio (ACLR) of 36dBc at output power of 28dBm. With a respective input and output return losses of 27.6dB and 13.2dB, the PA’s power gain is simulated to be 33.3dB while exhibiting an unconditional stability characteristic from DC to 3GHz. The monolithic microwave integrated circuit (MMIC) power amplifier (PA) is designed in 2 m InGaP/GaAs process. The proposed APD technique serves to be a good solution to improve the maximum linear output power of the UMTS PA without sacrificing other critical performance metrics.

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