A Gate-Leakage Insensitive 0.7-V 233-nW ECG Amplifier using Non-Feedback PMOS Pseudo-Resistors in 0.13-m N-well CMOS

electrocardiogram (ECG) amplifier by using the non-feedback PMOS pseudo-resistors is proposed. It consists of two operational-transconductance amplifiers (OTA) in series (a preamplifier and a variable-gain amplifier). To make it insensitive to the gate leakage current of the OTA input transistor, the feedback pseudo-resistor of the conventional ECG amplifier is moved to input branch between the OP amp summing node and the DC reference voltage. Also, an OTA circuit with a Gm boosting block without reducing the output resistance (Ro) is proposed to maximize the OTA DC gain. The measurements shows the frequency bandwidth from 7 Hz to 480 Hz, the midband gain programmable from 48.7 dB to 59.5 dB, the total harmonic distortion (THD) less than 1.21 % with a full voltage swing, and the power consumption of 233 nW in a 0.13 m CMOS process at the supply voltage of 0.7 V. Index Terms—Electrocardiogram amplifier, pseudo-resistor, gate leakage, low-voltage OTA I