US Patent 7484886 Bolometric on-chip temperature sensor

Disclosed are embodiments of an improved on-chip temperature sensing circuit, based on bolometry, which provides self calibration of the on-chip temperature sensors for ideality and an associated method of sensing temperature at a specific on-chip location. The circuit comprises a temperature sensor, an identical reference sensor with a thermally coupled heater and a comparator. The comparator is adapted to receive and compare the outputs from both the temperature and reference sensors and to drive the heater with current until the outputs match. Based on the current forced into the heater, the temperature rise of the reference sensor can be calculated, which in this state, is equal to that of the temperature sensor.