Sigma-delta noise shaping for digital-to-frequency and digital-to-RF-amplitude conversion

In this paper, we describe a new architecture of high-speed multibit ΣΔ noise shaping for digital-to-frequency conversion (DFC) and digital-to-RF-amplitude conversion (DRAC). The DFC and DRAC are instrumental in performing phase modulation (PM) and amplitude modulation (AM) of an RF polar transmitter. Since current biasing and continuous-time analog filtering of a conventional transmit modulator are avoided in this all-digital architecture, it is amenable to large-scale integration in an SoC realized in a digital deep-submicron CMOS process. The approach is demonstrated in the first single-chip fully-compliant GSM/EDGE transceiver realized in 90-nm CMOS.