Design of a Temperature Sensor Design Based on Sigma-Delta/Cyclic ADC

Being composed of a temperature sensing module and a Sigma- Delta/Cyclic ADC, a temperature sensor with a Sigma-Delta/Cyclic hybrid architecture ADC was designed based on CMOS 55 nm process. Adopting bipolar junction transistors (BJT) as temperature sensing devices, taking current mirror dynamic element matching, chopping and other technologies, the temperature sensing module was designed to improve the signal accuracy of the temperature sensing module. To achieve precise quantization of the output signal of the temperature sensing module, a Sigma-Delta/Cyclic hybrid architecture ADC was adopted. The high-order digital code was quantized by a first-order Sigma-Delta ADC, and then the low order digital code was quantized by a Cyclic ADC. The results show that compared with the structure that only used first-order Sigma-Delta ADC quantization, at least 50% of the conversion time can be saved with the Sigma-Delta/Cyclic hybrid architecture ADC. With a 2.5 V power supply and a 50 kHz clock input, the temperature sensor can achieve a 16 bit temperature measurement result within a conversion time of 30 ms. It can achieve a maximum temperature measurement error of ± 0.3 ℃ and a temperature measurement resolution of 4 m℃ within the temperature range of －45~125 ℃.