مهندسی مخابرات جنوب (Feb 2024)
Design and Simulation of Fourth Order Sigma-Delta Modulator using Parametric Amplifier with Dynamic Threshold for Digital Hearing Aid Application
Abstract
In this paper, a fourth-order, OTA-free, single-bit, low-consumption discrete-time (DT) delta-sigma (ΔΣ) modulator with CIFF structure is proposed for hearing aid applications. In portable medical devices such as hearing aids that are used permanently, the battery life and energy dissipation are very important. In a typical delta sigma modulator, the power-hungry parts are the OTA. Therefore, the elimination of OTAs is a challenge, and the proposed modulator uses new differential parametric amplifiers, with dynamic thresholde in even stages and inverter-based amplifiers in odd delta sigma stages instead of the OTAs. The dynamic threshold PMOS technique has been used for the first time in differential MPA, and the theoretical analyzes and simulations performed show better performance than the traditional method. Also, a chopper circuit is used on the first fstage to reduce the harmonics and flicker noise. The proposed differential modulator is simulated using standard 180 nm CMOS technology, which achieves 90.5 dB SFDR and 64 dB SNDR with an input bandwidth frequency of 10 kHz and an oversampling ratio of 128. The power supply is 1V and the FOMW were obtained as 3.43 PJ/step.
