A Novel Readout Circuit Allowing Microbolometers to Operate without TEC

This paper describes a new read-out IC (ROIC) architecture with substrate temperature compensation for the uncooled microbolometer detector. The influence of responsivity on the substrate temperature is evaluated. Numerical simulation and measurement of the proposed ROIC architecture demonstrate high quality of signal over wide temperature range without using multiple corrections. A 160 × 120 uncooled microbolometer focal plane array(FPA) based on the proposed circuit was implemented on silicon using a 0.5 μm CMOS technology. The measurement data show that the maximum difference of the output voltages is only 2mV over 20K substrate temperature change. This architecture is expected to allow removal of the thermoelectric cooler (TEC) from uncooled systems. Thus it is ideally suited for low-cost, low-power, and low-weight production applications.

I. Introduction(heading 1)

Thermal imaging market is today more and more attracted by systems with low power consumption[1]. One of the limiting elements is the present requirement for TEC, which is used to provide temperature stabilization for the microbolometer sensor array. The TEC and it's controller for an uncooled infrared system may require 500 to 2000 mW of power and 3 to 10 cm3 of additional volume [2]. Therefore the “TECless” operation of uncooled systems is the key step to fulfill the market requirement.