Design techniques for high intermediate frequency bandpass (sigma/delta) modulator.

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Title: Design techniques for high intermediate frequency bandpass (sigma/delta) modulator.
Author: Kode, Praveena
Abstract: The focus of the present thesis is the circuit -level implementation of an excess loop delay compensation scheme which optimizes excess loop delay in Analog -to -Digital Converter (ADC ) by using a programmable delay block and synchronizes the signal passing through Dynamic Element Matching block , used to mitigate mismatch effects of multi -bit Digital -to -Analog Converter (DAC ) . The proposed delay block has tuning range of T /10 to T /2 seconds , with a step size of T /30 seconds , where T is the time period (1 .25 nanoseconds ) of sampling signal (800 MHz ) in high IF (200 MHz ) Bandpass [sigma delta] ADC . The implementation details of the element rotation scheme used to calibrate the multi -bit DAC static error mismatch are also presented . Also presented is the design of high frequency highly linear Operational Transconductance Amplifier (OTA ) targeted for continuous -time filters in a high resolution High Intermediate Frequency (200 MHz ) Bandpass [sigma delta] ADC for Software Radio applications . Proposed OTA uses super source follower input stage to enhance its voltage -to -current conversion linearity . The design has been simulated using TSMC 0 .18 ?m CMOS process . The OTA has small signal transconductance of 0 .9 mA /V , IM3 below -79 dB (for 0 .3 Vpp input ) , Signal -to -Noise Ratio of 82 dB and power consumption of 6 .8 mW , when tested in unity gain configuration .
URI: http : / /hdl .handle .net /1969 .1 /86025
Date: 2008-10-10

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Design techniques for high intermediate frequency bandpass (sigma/delta) modulator.. Available electronically from http : / /hdl .handle .net /1969 .1 /86025 .

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