A CMOS Temperature Sensor Using Bank-Swap Dynamic Element Matching Technology

Abstract

A precision CMOS temperature-to-digital converter (TDC) for FBAR oscillator is presented in this work. The bank-swap dynamic element matching(DEM) technology is adopted in this circuit, which can reduce the mismatch error $\Delta m/m$ between different current mirrors by dynamically interchanging the current mirrors of the bias current circuit and the temperature core circuit using an additional current selector switch. In addition, a self-closing fast starting circuit ensures the front-end circuit to reach its desired operating point. This circuit is designed in TSMC $0.18\mu m$ CMOS process. The simulation results show that the static work current of the circuit is $52\mu A$ (@27°C) under the supply voltage of 1.8V. After two-point calibration correction, the temperature measurement accuracy achieved $-0.38^{\circ}C/+0.35^{\circ}C$ in the range of $-45^{\circ}C\sim 85^{\circ}C$. The core area of the circuit is $322 \mu m\times 441 \mu m$.