A Low Power Temperature to Frequency Converter for the On-Chip Temperature Measurement

In this paper, we are proposing a simple energy efficient on-chip temperature to frequency converter circuit. The proposed arrangement senses the temperature in terms of the proportional to absolute temperature (PTAT) current. The temperature equivalent PTAT current is then converted into frequency using the source coupled multivibrator circuit. The proposed circuit has been designed and fabricated in a standard 180-nm CMOS technology and occupies silicon area of ≈0.058 mm2. The measurements were performed on ten prototypes. The proposed architecture is capable of working in the temperature range of -40 °C to +85 °C with the supply voltage of 0.9 V ± 10%. The smart temperature sensor achieves a maximum temperature inaccuracy <;±1 °C after applying single point calibration. The average power consumption is ≈600 nW at +85 °C for 0.9 V supply voltage.