A 97dB, 21μW uncompensated CMOS Operational Amplifier Design for Biomedical Applications

In this paper the challenge of enhancing the gain and reducing the power requirement of amplifiers, preferably used in biomedical applications is addressed by demonstrating that composite cascode stages, operating in subthreshold/weak inversion regions provide a method of designing a ultra high gain (97dB) and low-power (21μW) op amp with 1.5V power supply. The op amp is designed without compensation capacitor. Additional advantages of this op amp design include low input noise and small chip area. Thus this design is applicable in biomedical applications where low power, low noise amplifiers, efficient in amplifying bio-signals in mHz-KHz range are required. The op amp is designed using 180nm CMOS technology and simulations that demonstrate results are given. Index Terms high gain, low power, low input noise, subthreshold, weak inversion, composite cascode. ________________________________________________________________________________________________________