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A Time-Domain Resolution Improvement of an RF-DAC

2010; Institute of Electrical and Electronics Engineers; Volume: 57; Issue: 7 Linguagem: Inglês

10.1109/tcsii.2010.2048485

1558-3791

Min Park, Michael H. Perrott, Robert Bogdan Staszewski,

Radio Frequency Integrated Circuit Design

We propose a time-domain technique that significantly improves resolution of an RF digital-to-analog converter (RF-DAC). As an alternative to resorting to various resolution improvement attempts in the amplitude domain or through quantization noise shaping, pulsewidth modulation (PWM) of a single least significant bit device is employed with fine timing accuracy easily afforded by advanced CMOS technology. The technique is examined in the context of a commercial Enhanced Data rates for GSM Evolution (EDGE) polar transmitter realized in 65-nm CMOS, which employs an amplitude modulator with basic 10-bit amplitude resolution limited by the RF-DAC switching device mismatches. Behavioral simulations include realistic device mismatches and show worst-case resolution improvement of 2.2 bits assuming 20-ps worst-case time granularity of the PWM signal controls.