Low-Voltage and High-Fidelity Audio Sigma Delta ADC Utilizing a Resolution Enhanced Quantizer with Frequency Domain Technique

학위논문 (박사)-- 서울대학교 대학원 : 전기·컴퓨터공학부, 2014. 2. 김수환.This thesis proposes a way to design the multi-bit quantizer of sigma delta ADC with less number of comparators than that of the conventional design with performance improvement. The method uses error-feedback based sigma delta modulation and additional analog differentiator and a digital integrator. Applying this method to the quantizer of a sigma delta ADC, results in the quantizer resolution enhancement and the order of sigma delta modulator increment with high enough overall resolution enhancement enough to reduce the OSR of main sigma delta integrators. Based on the conventional design method, additional efforts added to precisely estimate the performance of designed sigma delta ADCs. The method is applied and confirmed in sigma delta ADC for consumer electrics audio application with less than 3 dB SNR difference. The ADC uses 3rd order, 256 OSR, 4 level quantizer to achieve over 90 dB SNR for audio applications. Psychoacoustic properties are concerned for better audible performance. Performance of SNR 94.3 dB and THD+N -91.3 dB are measured for the sigma delta ADC core. This ADC implemented on 0.13 μm CMOS mixed-signal process with 3.3 V supply voltage operation. The proposed quantizer is applied to a low voltage audio sigma delta ADC. The ADC uses 1.2 V supply voltage with 0.13 μm CMOS mixed-signal process. The 100 dB SNR ADC is designed using 2nd order, 64 OSR, the quantizer with 2 comparators and additional digital logics. As expected, the sigma delta modulator shows adequate signal to quantization noise ratio performance with the proposed quantizer so that OSR can be reduced. The design achieves 102.5 dB SNR and 99.4 dB SNDR.제１장 서론 제１절 연구의 목적 제２절 배경 이론 제１항 ADC 기초 제２항 오디오 신호의 특성과 ADC의 특성 제２장 고품질 디지털 오디오 시스템을 위한 시그마 델타 ADC 제１절 ADC 노이즈원의 배분 제１항 열 잡음 제２항 양자화 노이즈 제３항 1/f 노이즈 제２절 시그마 델타 변조기의 구조 제３절 회로 구현 제４절 설계 검증 제５절 측정 결과 제６절 결론 제３장 저 전압 동작에 적합한 양자화 장치를 기반으로 한 오디오 ADC 제１절 저 전압 소자 사용에 대한 고려 제２절 시그마 델타 변조기의 구조 제３절 검증을 위한 설계 목표 제４절 전체 구조 제５절 회로 구현 제６절 설계 검증 제７절 결론 제４장 결론 및 차후 계획 참고 자료 AbstractDocto