A high-accuracy temperature sensor with an inaccuracy of ±1 °C From −55°C to 125 °C

A smart temperature sensor based on 0.35um ASMC CMOS process with an inaccuracy of ±1°C from -55°C to 125°C is presented. The sensor uses substrate vertical bipolar transistor to measure the temperature and errors resulting from nonidealities in the readout circuit are reduced to 0.1°C level by applying dynamic element matching (DEM) and chopping offset cancellation techniques. By using pseudo-random sequence, the mismatch of current mirrors can be reduced to smaller comparing with other methods. A voltage proportional to absolute temperature added to base-emitter voltage is used to compensate the process spread at one temperature with the trade off between inaccuracy and complexity. A digital output is realized by an on-chip sigma-delta ADC which is compatible with digital bus interface.