A novel instrumentation amplifier with high tunable gain and CMRR for biomedical applications

Authors: Riyaz Ahmad, AMIT JOSHI, Dharmendar Boolchandani

Abstract: A new design of current mode instrumentation amplifier (CMIA) with tunable gain and low voltage operation capability is proposed in this paper, which is suitable for biomedical signals processing, especially in electrocardiogram (ECG). It consists of a new design of current differencing transconductance amplifier (CDTA) and dual z copy CDTA (DZC-CDTA). The gain of the proposed CMIA is controlled by a MOS-based tunable resistor. The main advantage of the proposed CMIA is its high gain that can be tuned over a significant range with the help of two resistances. The performance of the proposed instrumentation amplifier is evaluated through simulation results on Cadence Virtuoso using SCL 180 nm CMOS technology. From simulation results gain, common mode rejection ratio (CMRR), power supply rejection ratio (PSRR), %THD and -3 dB bandwidth of proposed instrumentation amplifier are obtained as 55.09?81.12 dB, 90.42-116.5 dB, 97.3 dB (+PSRR), 114.2 dB (- PSRR), 1.5% and 9.5-165 kHz, respectively. The performance of the proposed design is also examined against PVT variations. The performance of proposed CMIA is compared with other existing designs available in the literature, which clearly shows the competency of the design. The post layout simulation results confirm the on-chip implementation feasibility.

Keywords: Biomedical signal processing, instrumentation amplifiers, current differencing transconductance amplifier(CDTA), current mode instrumentation amplifier (CMIA), high gain amplifiers, common mode rejection ratio (CMRR),power supply rejection ratio (PSRR)

Full Text: PDF