Hybrid quadrature polar modulator-based transmitter with digital predistorter for simultaneous enhancement of adjacent channel power ratios and power added efficiency (PAE)

The design and linearisation techniques for a highly efficient but nonlinear Class-E power amplifier (PA) applied to linear RF transmitters are presented. A hybrid quadrature polar modulator (HQPM) is proposed to linearise the Class-E PA. To accomplish this HQPM-based transmitter, the Class-E PA is designed with a consideration of finite DC-feed inductance for a wide supply voltage modulation bandwidth. In addition, a digital predistorter is embedded in the HQPM to provide the predistorted envelope modulation for both RF-input and supply voltage signals fed to the Class-E PA. A cdma2000 1times transmitter incorporating such a Class-E PA and a HQPM have been implemented to serve as an evidence for the simultaneous achievement of high linearity and high efficiency.