An Oscillator-Based CMOS Magneto-Sensitive Biosensor With In-Situ Switched Capacitor Calibration Scheme
This letter presents a high sensitivity oscillator-based magneto-sensitive biosensor. To suppress the environmental variations, e.g., voltage vibration, temperature drift, and lower the noise floor, an in-situ switched capacitor (ISSC) based calibration scheme is proposed with little cost on on-chip area and complexity. As an implementation example, a biosensor cell is designed in a standard 180-nm CMOS process. The ISSC scheme achieves an extra 13.2 dB suppression on the effective noise floor. The magnetic sensing capability of the presented biosensor is verified, indicating the frequency shift from one single magnetic nano-particle (MNP) with 500 nm diameter is 138.5 Hz and the dynamic range of detection is at least 80 dB.