A 2.5GHz delay-based wideband OFDM outphasing modulator in 45nm-LP CMOS

A 2.5 GHz delay-based CMOS outphasing transmitter for wideband OFDM is presented in 45nm LP CMOS. It dynamically delays LO edges to modulate the phase of two outphasing signals. A Tapped-Delay-Line coarse delay modulator allows delay modulation at the LO rate with no glitches. This is used to implement a 11-bit ΣΔ-dithered θ modulator with phase-domain filtering, and a 9-bit open-loop φ modulator. The system meets EVM and ACPR requirements for 802.11g at 2.5GHz.