A bridge-type resistive temperature sensor in CMOS technology with low stress sensitivity

CMOS resistive and bipolar temperature sensors are sensitive to mechanical stress via the piezoresistance and piezojunction effects. In this paper we present a CMOS compatible temperature sensor with differential output and low stress sensitivity. The sensor is based on 16 appropriately arranged p-well and p-poly resistors combined in a Wheatstone bridge in such a way as to provide isotropic piezoresistance for the sum of in-plane normal stress and to compensate the junction field effect. At room temperature the sensitivities with respect to temperature and stress were found to be 3.9mV/K and -29 uV /MPa, respectively. Hence, the sensor experiences a stress-related error as small as -0.0074K/MPa. In contrast to conventional bipolar approaches our sensor does not require any circuitry. Moreover, it can be placed easily at the desired location on the chip thanks to its small size of 61um × 61 um.