A Multi-loop high-PSR bandgap voltage reference with self-bias circuit for biopotential sensing

This paper presents a Brokaw bandgap voltage reference (BGR) for biopotential sensing. This design incorporates a collector common-mode voltage extraction feedback (CVEF) architecture for high power supply rejection (PSR) and a self-bias circuit for low power consumption. However, this combination of auxiliary circuits results in a complex, multi-loop system with a critical stability challenge not addressed by existing theoretical models. The primary contribution of this work is therefore a systematic stability analysis framework based on Mason's gain rule, which for the first time provides the complete analytical expressions for the loop gain's poles and zeros in such BGRs, yielding actionable design guidelines. Fabricated in a 0.18-μm CMOS BCD process, the proposed BGR validates this methodology, achieving a PSR of −98.58 dB at 100 Hz, directly enhancing the sensor's immunity to power-line interference, a minimum temperature coefficient (TC) of 8 ppm/^∘C from −40^∘C to 85 ^∘C, and consuming only 27.4 μW from a 5-V supply, confirming its suitability for portable sensor applications.