Design Considerations for a Direct Digitally Modulated WLAN Transmitter With Integrated Phase Path and Dynamic Impedance Modulation

Abstract

A 65-nm digitally modulated polar TX for WLAN 802.11g is fully integrated along with baseband digital filtering. The TX employs dynamic impedance modulation to improve efficiency at back-off powers. High-bandwidth phase modulation is achieved efficiently with an open-loop architecture. Operating from 1.2-V/1-V supplies, the TX delivers 16.8 dBm average power at -28-dB EVM with 24.5% drain efficiency, 22% PAE, 19.3% system efficiency, and 247-mW power consumption including the entire on-chip TX chain; the noise floor is -125 dBm/Hz at 200-MHz offset without external filtering.