A CMOS Temperature Independent Resistor Using a Bilinear Switched-Capacitor for Temperature Sensor

Abstract

High-precision analog circuits, such as integrated voltage references, are severely constrained by the intrinsic thermal drift of passive CMOS resistors, whose high Temperature Coefficients (TCs) fail to meet modern stability requirements (often <1 ppm/°C). This paper proposes a robust, nearly temperature-independent resistor utilizing a bilinear switched-capacitor (SC) circuit. By dynamically defining the equivalent resistance, the proposed architecture leverages the temperature characteristic of a capacitor—which is significantly smaller than that of a conventional resistor— thereby demonstrating superior temperature independence.
Simulation results demonstrate exceptional thermal robustness: the SC resistor achieved a TC of 1.25 ppm/°C range, representing a stability improvement of approximately 2.24 times over leading prior active and SC-based reference circuits. This work establishes the SC equivalent resistor as a high-precision, area-efficient, and electronically controllable reference solution.