A Multi-Level Pulse Modulated Polar Transmitter Using Digital Pulse-Width Modulation

This letter presents a multi-level pulse modulated polar transmitter architecture. Compared to a conventional gate-modulated envelope elimination and restoration transmitter, the use of the proposed technique is capable of reducing the in-band quantization noise level. Moreover, the proposed technique can increase the pulse-width modulation sampling frequency by relaxing its resolution requirement, which eases the filtering requirement at the output. A prototype transmitter system is constructed using commercially available components. Using a CDMA2000 1X signal at 836.5 MHz, it achieved over 40% power-added efficiency at 24.5 dBm output power level while passing the adjacent and alternate channel power ratios for the CDMA2000 standard.