A low-power CMOS smart temperature sensor for RFID application

摘要

This paper presents the design and implement of a CMOS smart temperature sensor, which consists of a low power analog front-end and a 12-bit low-power successive approximation register (SAR) analog-to-digital converter (ADC). The analog front-end generates a proportional-to-absolute-temperature (PTAT) voltage with MOSFET circuits operating in the sub-threshold region. A reference voltage is also generated and optimized in order to minimize the temperature error and the 12-bit SAR ADC is used to digitize the PTAT voltage. Using 0.18 μm CMOS technology, measurement results show that the temperature error is -0.69/C0.85 ℃ after one-point calibration over a temperature range of -40 to 100 ℃. Under a conversion speed of 1K samples/s, the power consumption is only 2.02 μW while the chip area is 230 × 225 μm~2, and it is suitable for RFID application.