A tunable bias-heating cancellation circuit for microbolometer readout electronics

Microbolometer sensors are commonly used in uncooled infrared focal plane arrays. However, they unavoidably suffer from severe bias heating during readout. This paper describes a simple and yet effective on-chip bias heating cancellation method based on the equivalence between the electrical and thermal systems and uses a capacitor to mimic the thermal capacitance of the bolometer. The cancellation can be tuned by adjusting the discharging current of the capacitor to overcome the discrepancies arising from the accuracy of the bolometer´s thermal parameters. The bias heating cancellation circuit is described in detail and the performance of the circuit is verified by simulation results. A test chip has been fabricated and the test results shows that the bias heating can be effectively cancelled