Low common-mode gain instrumentation amplifier architecture insensitive to resistor mismatches

In this paper, an instrumentation amplifier architecture for biological signal is proposed. First stage of conventional instrumentation amplifier architecture was modified by using fully balanced differential difference amplifier and evaluated by using 1P 2M 0.6μm CMOS process. From HSPICE simulation result, lower common-mode voltage can be achieved by proposed instrumentation amplifier architecture. Actual fabrication was done and six chips were evaluated. From the evaluation result, average commonmode gain of proposed instrumentation amplifier architecture is 10:84 dB lower than that of conventional one without requiring well-matched resistors. Therefore, the proposed instrumentation amplifier architecture is suitable for biological signal processing.