A 1.2-V 165-/spl mu/W 0.29-mm² Multibit Sigma-Delta ADC for Hearing Aids Using Nonlinear DACs and With Over 91 dB Dynamic-Range

Abstract

This paper describes the design and experimental evaluation of a multibit Sigma-Delta (ΣΔ) modulator (ΣΔM) with enhanced dynamic range (DR) through the use of nonlinear digital-to-analog converters (DACs) in the feedback paths. This nonlinearity imposes a trade-off between DR and distortion, which is well suited to the intended hearing aid application. The modulator proposed here uses a fully-differential self-biased amplifier and a 4-bit quantizer based on fully dynamic comparators employing MOS parametric pre-amplification to improve both energy and area efficiencies. A test chip was fabricated in a 130 nm digital CMOS technology, which includes the proposed modulator with nonlinear DACs and a modulator with conventional linear DACs, for comparison purposes. The measured results show that the ΣΔM using nonlinear DACs achieves an enhancement of the DR around 8.4 dB (to 91.4 dB). Power dissipation and silicon area are about the same for the two cases. The performance achieved is comparable to that of the best reported multibit ΣΔ ADCs, with the advantage of occupying less silicon area (7.5 times lower area when compared with the most energy efficient ΣΔM).

A 15‐MHz bandwidth double sampling MASH25b‐15b sigma‐delta modulator with DEM for multibit DACs

“…The sigma‐delta analog‐to‐digital converter (SD‐ADC) is the main candidate for high‐resolution applications due to their noise shaping mechanism and inherent immunity to the circuit nonidealities and has been widely used in many applications, such as communication systems, audio signal processing, and biomedical imaging systems . For the wideband applications, such as the popular medical ultrasound imaging (1‐15 MHz), the multistage noise shaping (MASH) structure is ideally suitable due to its potential for achieving higher resolution performance, wideband operation, and system stability .…”

“…The sigma-delta analog-to-digital converter (SD-ADC) is the main candidate for high-resolution applications due to their noise shaping mechanism and inherent immunity to the circuit nonidealities [1][2][3] and has been widely used in many applications, such as communication systems, [4][5][6] audio signal processing, [7][8][9] and biomedical imaging systems. [10][11][12] For the wideband applications, such as the popular medical ultrasound imaging (1)(2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14)(15), the multistage noise shaping (MASH) structure is ideally suitable due to its potential for achieving higher resolution performance, wideband operation, and system stability. 13 The linearity and SNDR of the modulator are expected to be as high as possible so that the imaging system could capture the analog biomedical input signal in its most original form and enhance the performance of imaging.…”

Hardware-Efficient Delta Sigma-Based Digital Signal Processing Circuits for the Internet-of-Things

“…However, if a higher resolution circuit is implemented, then the power, chip area and cost of the DSP circuits also increase. Delta Sigma technology can be an attractive solution for the aforementioned challenges and has been widely applied in biomedical circuits and systems [7][8][9][10][11][12] because of its unique properties. First, it is well known that a Delta Sigma analog-to-digital converter (ADC) has much less circuit complexity and lower power consumption than multi-bit ADCs.…”

Current mode sigma-delta modulator designed with the help of transistor’s size optimization tool

“…Analog solutions are also often applied in portable devices, where the power consumption and the circuit area are critical issues. Several interesting results regarding the A/D and D/A were discussed in [1][2][3]. Current mode circuits are good candidates to fulfill these requirements.…”