A pulse modulated polar transmitter for CDMA handsets

This paper presents a pulse modulated polar transmitter with the designed class-E power amplifiers for CDMA handsets. Compared to the conventional drain/collector-modulated envelope elimination and restoration transmitter, the presented implementation is capable of reducing circuit complexity and making the envelope and RF phase signals easily synchronized. A prototype transmitter system is constructed using commercially available components. Measuring using a CDMA IS-95 signal at 900 MHz, it achieves 49.3% efficiency at 26.6-dBm output power level while passing the adjacent and alternate channel power ratio requirements without using any pre-distortion or calibration. Moreover, the polar transmitter achieves more than 20 dB of output dynamic range.