A Power-Efficient Highly Linear Reconfigurable Biopotential Sensing Amplifier Using Gate-Balanced Pseudoresistors

A low-power reconfigurable biopotential sensing amplifier with highly linear feedback pseudoresistors is presented. Due to the gate-balanced pseudoresistors, amplifier linearity has been significantly improved, achieving a dynamic range more than 62.8 dB, with total harmonic distortion better than 60 dB across the whole bandwidth. An array of proposed amplifiers was fabricated in a 0.35-μm CMOS process. Measured input-referred noise is 2.81 μV rms with a midband gain of 40.3 dB. The noise efficiency factors corresponding to the bandwidth settings of 100 Hz, 1 kHz, and 10 kHz are 1.88, 1.93, and 2.05, respectively. Using a supply voltage of 2.5 V, each amplifier consumes 3.6 μA of current to achieve a bandwidth of 10 kHz, with a dynamic range of 63.7 dB. The electrocardiogram (ECG) measurement results are shown in this brief to substantiate the necessary low-frequency linearity improvement.