Linearity improvement of class-E Doherty amplifier using gm3 cancellation

Conventional Doherty amplifiers usually use a class-A or class-AB amplifier for the main amplifier to maintain high linearity while inherently showing low efficiency. Presented is a high efficiency Doherty amplifier that employs a class-E amplifier as the main amplifier and also improves the linearity using the g_m3 cancellation method. The g_m3 cancellation method is an effective way to remove third-order intermodulation distortion (IMD3) with proper gate voltage biasing for the auxiliary amplifier. The power added efficiency of the proposed Doherty amplifier is 52.8% with Pout of 28.5 dBm at 1.95 GHz. The IMD3 performance is improved by 11 dB compared to the Doherty amplifier without the gm3 cancellation method.