Delta-Sigma digital-RF modulation for high data rate transmitters

摘要: A low power, wideband wireless transmitter utilizing ∆Σ direct digital modulation of an RF carrier is presented. The architecture replaces high dynamic range analog circuits with speed and a passive LC bandpass filter, saving power area compared to conventional IQ modulators for systems. prototype IC built in 0.13 μm CMOS demonstrates data rate 1.2 Gb/s using OFDM bandwidth 200 MHz centered at 5.25 GHz. modulator consumes 187 mW occupies die 0.72 mm. quadrature digital-IF approach eliminates LO feedthrough image spurs from the output spectrum without requiring circuitry or system calibration, simplifying design transmitter. largest spur measured be -47 dBc. Measured SNDR over 43 dB. Successful implementation requires highQ, tunable modulator. 4th order filter center frequency GHz designed implemented differential coupled resonators. Variation response process temperature removed through automatic self-tuning loop that calibrates LO. 2.625 GS/s, 2nd order, 3-bit realized use pass-gate adder circuit optimized speed. software programmable support multiple bandwidths, channels, schemes. It can used adaptively transmit selected channels variable bit-rates, depending on channel conditions. envisioned digital-RF as universal systems applications require rates consumption. Thesis Supervisor: Charles G. Sodini Title: Professor