0.3-V Nanopower Biopotential Low-Pass Filter

Tomasz Kulej,Montree Kumngern,Fabian Khateb

doi:10.1109/access.2020.3005715

Abstract

This paper presents a compact power-efficient CMOS fourth-order low-pass filter suitable for electrocardiogram (ECG) acquisition systems. The CMOS structure of the proposed filter utilize the bulk-driven technique and operates in subthreshold region to achieve extremely low-voltage supply (0.3V) and nanopower consumption (0.676 nW) for cut-off frequency of 100 Hz. The filter was designed and simulated using $0.18~\mu \text{m}$ CMOS TSMC technology. The total input referred noise of the filter is $87~\mu $ Vrms and the dynamic range is 58.1 dB. The filter offers the best figure of merit of $2.91\times 10^{-14}$ J, the lowest power consumption and voltage supply, compared with the previous state-of-the-art nanowatt filter designs.

Highlights

In recent years, an increased interest in the design of ultralow-voltage (ULV) and ultra-low-power (ULP) electronic systems, devoted to biomedical applications, is observed
The signal is converted into digital form by an analog-to-digital converter (ADC) [1], [2]
The BD circuits proved their capability to operate from extremely low VDD, even much below the threshold voltage (VTH) of MOS transistors, while maintaining the input common mode range (ICMR) almost rail-to-rail [7]–[13]

Summary

INTRODUCTION

An increased interest in the design of ultralow-voltage (ULV) and ultra-low-power (ULP) electronic systems, devoted to biomedical applications, is observed. The BD circuits proved their capability to operate from extremely low VDD, even much below the threshold voltage (VTH) of MOS transistors, while maintaining the input common mode range (ICMR) almost rail-to-rail [7]–[13] It is worth noting, that in some cases the BD approach can extend the DR of analog circuit under ULV supply, since it can extend the input range for which. The equivalent block diagram of the proposed biquad may be presented in the form shown in Fig.2.b where gmn = gm3B It is worth pointing out, that due to the non-tailed architecture of the first transconductor, the minimum supply voltage of the proposed biquad filter is as low as 2VDSsat, where VDSsat is the saturation voltage of an MOS transistor (3-4 UT in weak inversion region). Because of the negative feedback loop, the maximum (minimum) output voltage can be very close to supply rails

TRANSFER FUNCTION

NOISE PERFORMANCE

CONCLUSION