Continuous-time CMOS adaptive asynchronous (SIGMA)(DELTA) modulator approximating low-f_(s) low-inband-error on-chip wideband power amplifier

摘要

A mixed-signal continuous-time-processing standard CMOS implementation of an asynchronous sigma-delta modulator aimed to drive a switching amplifier operating as an on-chip wideband adaptive power supply is presented in this work. The paper first briefly discusses the fundamental limit tracking capabilities of a two-level switching signal to inband-error-free track a bandlimited signal with minimum average switching frequency. It is argued the adequacy of an adaptive asynchronous sigma-delta modulator (AA(SIGMA)(DELTA)) to approximate such fundamental characteristics. The second part of the paper presents mixed-signal design details of the various subcircuits implementing a CMOS low-power digitally-programmable AA(SIGMA)(DELTA) modulator, with 7 MHz average switching frequency operation and 1000 (mu)m X 640 (mu)m area occupancy.