Precise modeling of thermal memory effect for power amplifier using multi-stage thermal RC-ladder network

A precise modeling method for thermal memory effect has been proposed. The proposed method consists of a multi-stage thermal RC-ladder network, which has been replaced from heat diffusion equation. Different from conventional method, the proposed method is valid for both steady state solutions and transient solutions. As examples, output voltage transient phenomena and 3rd order inter modulation distortion characteristics for InGaP/GaAs HBT amplifiers were simulated and measured. Experimental results support the validity of the proposed method. The model can be used for accurate design for supper linear microwave power amplifiers and linearizers.