Application of the 1N4148 Diode to Temperature Measurements Between −140 °C and 5 °C

The temperature-voltage relationship of a 1N4148 diode temperature sensor was investigated for temperatures between 5 °C and -140 °C. The ambient air inside a half-filled nitrogen dewar flask was used to provide a temperature ramping mechanism that ranged from room temperature to -140 °C. The 1N4148 diode temperature sensor produced a sensitivity of 2.25 mV/K in the temperature range of 0 °C to -65 °C. This sensitivity value further fell to 2.10 mV/K in the -65 °C to -140 °C temperature range. It was therefore concluded that even though the 1N4148 diode has linear voltage variation with temperature in the investigated range, its sensitivity generally tends to decrease with decreasing temperature.