A fully integrated low noise CMOS instrumentation amplifier design for low-power biosensors

This paper presents the design of a monolithic low power CMOS low-noise instrumentation amplifier (INA) for low-power biosensor applications. To achieve high-fidelity cardiac signal acquisition, the INA circuit and system design requirements are discussed. Design strategies for mitigating the in-band flicker noise and thermal noise using chopper-stabilization and current scaling techniques are investigated. Sub-threshold operation is also utilized to reduce power. The INA achieves a simulated noise spectral density of 39.9 nV/√Hz from dc to 300Hz in 4.6μW, with an outstanding noise efficiency factor (NEF) of 2.47.