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Download or read book Wideband Discrete-time Delta-sigma Analog-to-digital Converters with Shifted Loop Delays written by Xin Meng and published by . This book was released on 2015 with total page 79 pages. Available in PDF, EPUB and Kindle. Book excerpt: Low-distortion architecture is widely used in wideband discrete-time switched-capacitor delta-sigma ADC design. However, it suffers from the power-hungry active adder and critical timing for quantization and dynamic element matching (DEM). To solve this problem, this dissertation presents a delta-sigma modulator architecture with shifted loop delays. In this project, shifted loop delays (SLD) technique can relax the speed requirements of the quantizer and the dynamic element matching (DEM) block, and eliminate the active adder. An implemented 0.18 um CMOS prototype with the proposed architecture provided 81.6 dB SNDR, 81.8 dB dynamic range, and -95.6 dB THD in a signal bandwidth of 4 MHz. It dissipates 19.2 mW with a 1.6 V power supply. The conventional low-distortion ADC was also implemented on the same chip for comparison. The new circuit has superior performance, and dissipates 25% less power (19.2 mW vs. 24.9 mW) than the conventional one. The figure-of-merit for the ADC with SLD is among the best reported for wideband discrete-time ADCs, and is almost 40% better than that of the conventional ADC. The second project describes two techniques to enhance the noise shaping function in the proposed low-distortion [delta sigma] modulator with shifted loop delays. One is self-noise coupling based on low-distortion [delta sigma] structure; the other is noise-coupled time-interleaved [delta sigma] modulator. Both architectures use shifted loop delays to relax the critical timing constraints in the modulator feedback path, then to save power consumption of each block in the modulators. Two [delta sigma] ADCs were analyzed and simulated in a 0.18 um CMOS technology. The simulation results highly verify the effectiveness of the proposed structure. The third system describes the design technique for double-sampled wideband [delta sigma] ADCs with shifted loop delays (SLD). The added loop delay in the feedback branch relaxes the critical timing for DEM logic. Delay shifting can be combined with such useful techniques as low-distortion circuitry and noise coupling for wideband [delta sigma] modulators. The presented techniques relax the timing for inherent quantization delay, reduce the speed requirements for the critical circuit blocks, and achieve power efficiency by replacing the power-hungry blocks normally used in the modulators. Analysis of all architectures allows the choice of the most power-efficient topology for a wideband [delta sigma] modulator. The proposed second-order and third-order [delta sigma] modulators were designed and simulated to verify the effectiveness of the shifted loop delays techniques.