New Feedback Architecture for VCO-Based Delta-Sigma ADCs Utilizing Phase Shifter

• 作 者: Ali Mohammadi Ahmad Ayatollahi Adib Abrishamifar
• 机 构: School of Electrical Engineering, Iran University of Science and Technology,
• 出 处: Journal of Electronic Science and Technology
• 发表日期: 2012年03期
• 关键词: analog Feedback converter oscillator mismatch nonlinearity illustrated delta beh

The voltage controlled oscillator-based (VCO-based) continuous-time delta-sigma (CTDS) analog to digital converter (ADC) suffers from nonlinearity and mismatch in its feedback network. A new feedback network consisting of a phase shifter is proposed. The phase shifter replaces the digital to analog converter (DAC) in the proposed architecture. Feasibility of the proposed idea is discussed and its higher performance is illustrated through a behavioral simulation approach (CppSim). We have also developed the phase shifter as a variable all-pass filter in the C language. The nonlinearity and mismatch of the system caused by DAC is mitigated, resulting in higher signal to noise ratio (SNR) and signal to noise and distortion ratio (SNDR), respectively.

The voltage controlled oscillator-based (VCO-based) continuous-time delta-sigma (CTDS) analog to digital converter (ADC) suffers from nonlinearity and mismatch in its feedback network. A new feedback network consisting of a phase shifter is proposed. phase shifter replaces the digital to analog converter (DAC) in the proposed architecture. Feasibility of the proposed idea is discussed and its higher performance is illustrated through a behavioral simulation approach (CppSim). We have also developed the phase shifter as a variable all- pass filter in the C language. The nonlinearity and mismatch of the system caused by DAC is mitigated, resulting in higher signal to noise ratio (SNR) and signal to noise and distortion ratio (SNDR), respectively.