کنفرانس بین المللی میکروالکترونیک ایران

صفحه اصلی / هفتمین کنفرانس بین المللی میکروالکترونیک ایران

A -73.3 dB-THD ±285 mV DC Offset Rejection Analog Front-End with Novel Chopper Spike Filter for Wireless Wearable ECG Sensors

نویسندگان :

Mahsa Sadeghi¹ Mohammad Yavari²

1- دانشگاه صنعتی امیرکبیر 2- دانشگاه صنعتی امیرکبیر

کلمات کلیدی :

ECG Sensors،Improved Folded-Cascode Amplifier،Chopper Capacitively-Coupled Instrumentation Amplifier (CCIA)،Electrode DC Offset Removal،Chopper Spike Filter (CSF)

چکیده :

In this paper, a low-noise, low power analog front-end (AFE) for wireless wearable electrocardiogram (ECG) sensors is proposed. A chopper-capacitively coupled instrumentation amplifier (CCIA) is employed to amplify the cardiac signal and effectively suppress flicker noise. To achieve higher gain, a folded cascode structure is used, which incorporates source degeneration technique to reduce thermal noise. To enhance the input impedance, a positive feedback loop (PFL) is employed and a DC servo loop (DSL) is utilized to eliminate the electrode DC offset. Furthermore, a novel chopper spike filter (CSF) with high linearity and low-noise is proposed to further suppress spikes and ripples generated by the chopper technique, which helps using smaller capacitors in the DSL. Finally, a programmable gain amplifier (PGA) is employed to adjust the amplification of the cardiac signal based on its amplitude. The AFE achieves measured closed-loop gain of 58.5, 52.4, 46.4, 40.4 dB over a bandwidth of 0.2-330 Hz. The proposed AFE has been simulated with Cadence using 180nm CMOS process with a 1.8V power supply. It consumes 2.44 µA current and has a noise efficiency factor (NEF) of 6.15, and a THD of -73.7 dB at a 16 mVPP input signal. It achieves CMRR 96.7 dB, input impedance 1.8 GΩ at 10 Hz, and dc suppression as large as ±285 mV.