High CMRR Current-Mode Instrumentation Amplifier for Low Voltage and Low Power Applications

Abstract

This paper introduces a current-mode instrumentation amplifier circuit which employs one modified dual-X current conveyor transconductance amplifier only. The proposed instrumentation amplifier circuit is operated at ±0.75 V and consumes maximum power of 0.64 mW only, thus suitable to low voltage, low power applications. The proposed circuit also has the feature of cascadability as outputs are explicitly taken from high output impedance terminals. The differential mode gain of the proposed circuit is electronically tunable and less affected by the temperature variation. Additionally, differential mode gain is bandwidth independent as well. Moreover, the common mode rejection ratio of the circuit is 175 dB at lower frequencies and remains as high as 38 dB at 100 MHz. The non-ideal and parasitic analyses of proposed instrumentation amplifier are also discussed. The effects of threshold voltage variation of MOS transistors on differential mode gain are further examined. PSPICE simulations with 0.13 µm CMOS process parameters are performed to confirm the theoretical proposals. Furthermore, the proposed circuit is also tested experimentally via commercially available ICs (AD844 and LM13700).