A Time Domain differential CMOS Temperature Sensor with Reduced Supply Sensitivity

In this paper, a time domain CMOS temperature sensor with differential temperature sensing circuit and reduced supply sensitivity is presented. Differential temperature sensing is achieved by using two delay generators, each for generating positively and negatively proportional to temperature delays respectively. The effective temperature signal can then be increased for quantization. The variation in supply voltage is sensed and converted to bias currents proportional to supply voltage. Temperature error due to 10% supply voltage variation can be reduced to less than plusmn1degC. A temperature dependent pulse will be generated and then digitized by a ripple counter using an external clock signal. Simulation results show that a plusmn0.6degC with two-point calibration can be achieved with a temperature variation from 0degC to 100degC. The circuit consumes 12 muA and 70 muA in static and temperature acquiring mode, respectively, and has a sampling rate of more than 80 k samples/s.