A Linearity-Enhanced Compact Series-Type Doherty Amplifier Suitable for CDMA Handset Applications

A high-linearity series-type Doherty amplifier that does not use bulky 3 dB quadrature hybrid coupler is developed for mobile handset applications. A predistorter is employed at the input to improve the ACPR performance at the high-power region, which effectively extends maximum linear power range. For size and stability considerations, the phasing circuits between the carrier and peak amplifiers have been realized using high-pass T-networks. The series-type Doherty amplifier of this work shows PAE's of 18% and 42.8% at 16 dBm and 28 dBm, while meeting the IS-95A ACPR requirement of -42 dBc