Session 21-4

A 80kS/s 36µW Resistor-based Temperature Sensor
using BGR-free SAR ADC with a Unevenly-weighted Resistor
String in 0.18µm CMOS

 

Abstract

A resistor-based temperature sensor with a BGR-free SAR ADC is reported. The non-zero temperature dependency of the ADC reference voltages, as a result of without using a BGR, is compensated by adopting the proposed unevenly-weighted 9-bit resistor string for reference voltage generation. Fabricated in a 0.18µm CMOS, the sensor achieves 0.25°C resolution over 0~100°C range and draws 20µA from a 1.8V supply. At a conversion rate of 80kS/s, the FOM[1] is 0.11nJ/°C.