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This paper presents an innovative general structure for a single-loop Sigma-Delta (Σ Δ) modulator that combines low-distortion and noise-coupled techniques to achieve high-resolution for low-power applications. The low-distortion technique adjusts the signal transfer function of the proposed structure to unity, while the noise-coupled technique enhances the order of quantization noise-shaping at the modulator output. These techniques were incorporated into the design to increase the modulator order without requiring additional operational amplifiers during its circuit implementation, resulting in a low-power modulator compared to similar structures. To reduce the number of required amplifiers, a second-order infinite impulse response (IIR) filter was used in the modulator loop filter, in place of two integrators. To assess the proposed structure's performance, a third-order modulator sample was implemented and simulated for speech recognition applications, specifically, digital hearing aids, using 180 nm complementary metal oxide semiconductor (CMOS) technology. The results indicate that for a third structure with a sampling rate of 64, an input sine signal of −6 dBFS and a sampling frequency of 2.56 MHz, the signal to noise plus distortion (SNDR) was 81.9 dB, and the dynamic range (DR) was 88 dB for a 20 KHz bandwidth. The modulator's power consumption was 126.9 μ W. Circuit and system-level simulations demonstrate the effectiveness of the proposed method. [ABSTRACT FROM AUTHOR]

In tills paper a second-order low distortion Sigma-Delta Modulator (EAM) with utilization of Comparator-Based Switched-Capacitor (CBSC)-based IIR filter, is explored. The advantages of this new structure are justified by the reduction of power and area. For this purpose IIR filter block can be made with single CBSC gain stage that has the same accuracy and performance of second-order filter with two Op-amps. The design of CBSC gain stages is intended to minimize the power consumption, and maximize Modulator performance. As shown in the simulation result, for a 20-KHz signal bandwidth, the modulator achieves a dynamic range of 70.2 dB and a peak signal-to-noise and distortion ratio (SNDR) of 68 dB with an over-sampling ratio of 64. In addition it consumes only 198/xW from a 1.8-V power supply at 2.56 MS/s. [ABSTRACT FROM AUTHOR]