Design of High Gain and High Slew Rate Two-Stage CMOS Operational Amplifier for Medical Instrumentation

Abstract Weak signals such as heart beats are not easily detectable by the instrumentation device called Electrocardiogram (ECG); rather, it requires amplification. This requires research to design a high-gain operational amplifier (op-amp). Using compensation approach and 0.35µm complementary metal-oxide semiconductor (CMOS) technology, the study was constructed and simulated a high gain two-stage CMOS operational amplifier. At a 2.5V power supply, the intended circuit runs. In addition, mathematical formulas were used to carry out the analytical design. With the aid of the design and simulation program PSPICE design and simulation software, the circuit was simulated and examined. The result shows that the designed two-stage CMOS op-amp was an excellent open loop gain of 131.223dB, a slew rate of ±10V/µs, a Common Mode Rejection Ratio (CMRR) of 132.210dB (decibles), and a unity gain frequency of 13.012MHz.The obtained result depicted a high-gain two-stage CMOS op-amp was designed.This gain is obtained by using a high-bias current. So, this circuit could be used to amplify weak signals in the instrumentation device due to its excellent gain. In addition, the circuit has a high slew rate, so this circuit is applicable to amplify weak signals quickly.