Use of a Delta-Sigma Modulator in the Amplitude Path for Polar Modulation

摘要

A multiple bit sigma-delta modulator is used in the amplitude path for polar modulation. This shifts the quantization noise up in frequency, away from the wanted signal and thus simplified filtering, enabling it to be performed on-chip. Dithering based on a pseudorandom sequence in the delta-sigma modulation quantizer whitens and shapes the quantization noise. Dynamic element matching based on the same pseudorandom sequence varies the transistors used in the digital to analogue final stage, thus mitigating the effect of mismatching between these transistors. Contains a binary to thermometer encoder.