Improved Envelope Injection and Termination (EIT) RF Power Amplifier With Envelope Equalization for Mobile Terminal Applications

An improved envelope equalization technique to enhance the efficiency of envelope injection and termination RF power amplifiers (PAs) is proposed. A TriQuint heterostructure field-effect transistor PA, which draws 100 mA from an 8.0-V supply and provides maximum power of 28 dBm for a continuous-wave input at 1.95 GHz, exhibits a significant improvement in the maximum linearity compliant efficiency from 21% to 28% using the proposed technique for an uplink WCDMA signal with 6.9-dB peak-to-average power ratio. The equalization improves the amplifier linearity by reducing the clipping distortion extending the maximum linear output power by more than 1 dB. A technique to maintain high efficiency, even at low average powers, is also described.