A Time-Domain CMOS Temperature Sensor Using Gated Ring Oscillator With Linearity Optimization

This paper presents a time-domain CMOS temperature sensor with linearity optimization. We employ a bipolar junction transistor (BJT)-based frontend together with an on-chip temperature-compensated gated ring oscillator (GRO) with intrinsic first-order noise shaping to achieve both high linearity and accuracy. This work also systemically optimizes the nonlinearity introduced by: 1) the curvature of VBE;2) the voltage-to-time conversion; and 3) the quantization error. Implemented in a standard 0.18-μm CMOS process, this work demonstrates an inaccuracy of ±0.35
^°
C and a conversion time of 0.165ms over a wide temperature range from -40 to 125
^°
C, featuring a favorable accuracy- and resolution-FOM of 0.64nJ