A Silicon Semiconductor Temperature Sensor Applied for RFID Tag

Abstract

A new type of silicon semiconductor temperature sensor applied for RFID tag chip is designed based on the linear temperature characteristic of base-emitter voltage of parasitic substrate PNP transistor. A novel switched capacitor integrator based on positive-negative synchronous integration is introduced to amplify the weak temperature signal precisely and provide a method to represent the temperature in analog domain. Temperature quantization is accomplished by a 12-bit ultra-low-power successive approximation analog-to-digital converter providing a resolution of 0.03125°C/LSB. The circuit was simulated by using device model of 0.18-μm CMOS process. The output integration swing is 2VPP and the average current dissipation is 38.91μA at 1.8V supply. The sensor achieves an accuracy of -0.1°C to +0.33°C in the temperature range of -39°C to 89°C.