Noise Limitations of the Applications of Miniature Thermal Resistors

The limitations of the performance of thermal resistors due to the electronic noises are investigated. Two applications of the thermistors are considered: the thermometer and the bolometer. The speed of the response of the probe is kept in mind in the calculation of the noise bandwidth. The effects of three different types of noises having white, 1/f, and Lorentzian frequency spectra are treated. The noise equivalent instabilities of the measured temperature are calculated and also converted to fluctuations of the power in bolometers. The detectable minimum of short energy pulses is also investigated. The numeric examples show that in the case of platinum resistors the main limitation of the accuracy is the thermal noise, while in semiconductor thermistors the excess noises can have significance.