Multi-threshold transistors cell for Low Voltage temperature sensing applications

A new Low Voltage CMOS temperature sensor with low supply sensitivity is introduced. Though operation over a large temperature range is possible, this structure is particularly useful in power/thermal management applications where a rather narrow temperature band is of most concern. The sensor is based upon a multi-threshold 4 transistors cell and uses the temperature dependence of the threshold voltages to sense temperature. The low headroom requirement of the structure allows for very low voltage operation or practical cascoding at nominal supply voltages to further reduce the supply voltage sensitivity. With proper device sizing, a very linear relationship between output voltage and temperature is achieved. Simulation results show that the temperature linearity is robustness to process variations and the cascoded implementation has excellent insensitivity to the power supply voltage. The circuit has been implemented in a 65nm digital process with multiple threshold voltages devices. Simulation results show a temperature nonlinearity of less than 0.5°C over the temperature range of 100~150°C.