OTA-C Filter Based on the Low Noise and HD3 Transconductance for ECG Detection $\sim$

This paper presents a 5-order low-pass filter (LPF) structure based on the operational transconductance amplifier(OTA) structure that is designed with low noise and HD3. To ensure that the filter has a lower power dissipation, noise, and third harmonic distortion(HD3), the OTA operates in weak inversion region and uses technology including current division, current cancellation, source degeneration. The LPF is simulated by the 0.18 µm CMOS process, and the results show that the LPF locates within 250Hz and consumes 65.49 µW, the ripple is less than 0.2dB, and the HD3 is less than -70.21dB (@50mV). The maximum input reference noise (IRN) is $71.86\ \mu V/\sqrt{Hz}$ The proposed LPF is suitable for Electrocardiograph (ECG) signal detection analog front circuit.