A 2.16-mu W Low-Power Continuous-Time Delta-Sigma Modulator With Improved-Linearity G(m) for Wearable ECG Application

Abstract

This brief presents a 2.16 mu W low-power third-order single-bit continuous-time delta-sigma modulator (CTDSM) for electrocardiogram (ECG) signal acquisition application. The proposed CTDSM uses an active-RC (A-RC) integrator as a first integrator and an improved linearized G(m)-C integrator for the second and third integrators, respectively. The mixed-integrator structure helps to mitigate the trade-offs between power consumption and resolution. Moreover, a source-degenerated auxiliary differential pair circuit is used for the G(m)-C integrators to improve their linearity. By using A-RC and G(m)-C integrators together along with an improved-linearized G(m) block, the total power consumption was measured as 2.16 mu W with a peak signal-to-noise ratio of 80.1 dB, signal-to-noise, and distortion ratio of 78.4 dB, and a dynamic range of 81.4 dB with a bandwidth of 250 Hz. Furthermore, a real-time ECG signal was successfully captured in an ECG acquisition system that consisted a heart-rate sensor and a signal acquisition circuit, including the proposed CTDSM.