Systematic Design of CMOS Swit

The current explosion of interest in the realizaTIon of mixed-signal systems onchip using VLSI technologies has moTIvated the use of oversampling Sigma-DeltaAnalog-to-Digital Converters (ADCs) to implement the front-end of such systems.This type of ADCs, composed of a low-resoluTIon quanTIzer embedded in afeedback loop, uses oversampling (a sampling frequency much larger than theNyquist frequency) to reduce the quantization noise and modulation [Inos62] topush this noise out of the signal band. The combined use of redundant temporal data (oversampling) and filtering modulation) results in high-resolution, robustADCs, which have lower sensitivity to circuitry imperfections and are more suitable than traditional Nyquist-rate ADCs for the implementation of Analog-to-Digital(A/D) interfaces in a standard CMOS technology.The efficiency of ADCs has been demonstrated in a large number of ADCIntegrated Circuits (ICs) for digitizing lowpass signals with diverse bandwidths and applications [Nors97][Mede99]. Recently, the principle of modulation has beenextended to bandpass signals, leading to a new type of ADCs, named BandPassADC [Schr89], which are especially suited to convert bandpasssignals with a narrow bandwidth. This has an obvious application at the front-end of modern wireless communication systems such as mobile phones, digital radioreceivers, etc.have much in common with their lowpass counterparts – whosebasic properties and limitations have been described elsewhere [Nors97][Mede99].However, there are some issues which are peculiar to This chapter is devoted to the description of these issues. In Section 1.2, digital radio receivers aredescribed, pointing out the need for an ADC at the IF location. Section 1.3 and Section 1.4 give an overview of ADCs. Section 1.5, Section 1.6 and Section 1.7explain the basic concepts and architectural issues of , Finally, Section 1.8 summarizes the performance of state-of-the-art.