Design and Simulation of Ultra-Low-Power Sigma-Delta Converter Using the Fully Differential Inverter-Based Amplifier for Digital Hearing Aids Application

In this paper, an ultra-low-power, second-order, discrete-time sigma-delta converter is proposed for hearing aids application. In portable biomedical devices such as hearing aids that permanently use, the battery lifetime and power dissipation are very considerable. In a typical delta-sigma modulator, the OTAs are the most power-consuming parts. The OTAs elimination in the converters is now challenging. Therefore the converter with a self-biased fully differential inverter-based amplifier was designed with only 1.15 µw static power dissipation at a 1-volt power supply. The inverter-based amplifier was used instead of the OTAs in two stages of the modulator. The modulator’s structure is CIFB, single-loop, and single bit. The proposed differential modulator was designed and simulated using a standard 180 nm CMOS technology, which obtained SFDR and SNDR of 95.2878 dB and 64.004 dB, respectively. The sampling frequency is considered 2.56 MHz, and the input signal bandwidth is 10kHz. The modulator consumes power just about 5.1091 µW, and the FOMW achieves 0.197 pj/step.