A Distributed Linearization Technique for Multistage High Power Amplifiers

The paper describes a linearization technique applicable to cascaded multi device power amplifiers. It is based on distributed amplification and signal injection and is particularly suitable for monolithic integrated solutions. It exploits the bias dependence of the transconductance, but focuses on the IMD products and their controlled generation and cancellation, rather than on the shape of the transconductance and its derivatives. The technique is capable of positively influencing the linearity, including the near back-off power range prior to 1 dB compression point. 30 W monolithic PA is designed and fabricated using Philips 4 Gen LDMOS MMIC process. Simulation and measurement results are in good agreement. 8-10 dB IMD3 improvement is observed under 2-tone conditions and 5-6 dB ACLR and IMD3 reduction with 2C-WCDMA signal