Adaptive correction techniques for delta-sigma A/D converters

• Main Author: Abdennadher, Salem
• Other Authors: Kiaei, Sayfe
• Language: en_US
• Published: 2013
• Subjects: Analog-to-digital converters; Adaptive signal processing; Cascade converters
• Online Access: http://hdl.handle.net/1957/36199

Oversampling analog-to-digital and digital-to-analog converters are gaining more popularity in many signal processing applications. Delta-sigma modulators are used in practical applications of oversampling systems because of their apparent practical advantage over other oversampling converters in terms of insensitivity to the inevitable imperfection of the analog circuitry. In Δ∑ modulators, analog integrators are always very important components and are usually modeled as ideal in real applications. However, theoretical analysis shows that the integrator nonideality due to capacitor mismatching and finite op-amp gain cause large signal-to-noise ratio degradation. The primary disadvantages of the dual-quantization and cascade modulators are that they rely on the precise cancellation of terms derived from two separate circuits, one analog and one digital, and that there are added complexities on the digital sides. This thesis describes digital adaptive correction of nonidealities in dual-quantization and cascade modulators. The sources and effects of nonidealities in a first-order delta-sigma loop are analyzed. Simple correction schemes are presented, and theoretical SNR improvements are calculated and compared with simulation results. === Graduation date: 1993