Infrared sensor amplification techniques for thermal imaging

A thermal imaging apparatus, comprising:

• an infrared (IR) camera module comprising an IR sensor for detecting IR radiation from a target scene, the IR sensor comprising a plurality of IR sensor elements arranged to receive the IR radiation from the target scene, each IR sensor element corresponding to part of a thermal image of the target scene and configured to produce an IR sensor element output signal based on an electrical characteristic that varies corresponding to an amount of the IR radiation received by the IR sensor element;
• an amplifier stage coupled to the IR sensor for receiving the IR sensor element output signals from each of the plurality of IR sensor elements, the amplifier stage comprising a gain for amplifying the IR sensor element output signal from each of the plurality of IR sensor elements to generate amplifier output signals corresponding to each of the plurality of IR sensor elements, the gain provided according to a continuous gain function having a first gain region and a second gain region and configured to amplify the each of the IR sensor element output signals through a continuous range of IR sensor element output values to generate the corresponding amplifier output signals with a corresponding continuous range of amplifier output values, and
• saturation circuitry configured to, for each of the IR sensor element output signals, reduce the gain of the amplifier stage according to the continuous gain function in the event that the corresponding amplifier output signal meets a threshold value below a maximum amplifier output such that, for each of the IR sensor elements, if the first gain region applied to the IR sensor element output signal results in the corresponding amplifier output signal meeting the threshold value, the saturation circuitry reduces the gain applied to that IR sensor element output signal so that the second gain region is applied to the IR sensor element output signal;
• and
• processing circuitry coupled to the amplifier stage and configured to generate the thermal image of the target scene based on each of the amplifier output signals corresponding to the respective IR sensor element output signals from each of the plurality of IR sensor elements.

A method, comprising:

• receiving a plurality of IR sensor element output signals corresponding to an amount of infrared radiation received by each of a plurality of IR sensor elements from a target scene, each of the IR sensor elements corresponding to a part of a thermal image of the target scene;
• amplifying each of the IR sensor element output signals with a gain of an amplifier stage to generate a plurality of amplifier output signals, each of the plurality of amplifier output signals corresponding to one of the plurality of IR sensor elements, the gain provided according to a continuous gain function configured to amplify each of the IR sensor element output signals through a continuous range of IR sensor element output values to generate the corresponding amplifier output signal with a corresponding continuous range of amplifier output values, wherein for each of the IR sensor element output signals, the amplifying of the IR sensor element output signal comprises:
• if the IR sensor element output signal is within a first range of IR sensor element output signals, applying a first gain region of the continuous gain function to the IR sensor element output signal to generate an amplifier output value within a corresponding first range of amplifier output values, and
• if the IR sensor element output signal is within a second range of IR sensor element output signals, applying a second gain region of the continuous gain function to the IR sensor element output signal to generate an amplifier output value within a corresponding second range of amplifier output values, wherein
• the second range of IR sensor element output signals comprises IR sensor element output signals such that applying the first gain region to such IR sensor element output signals generates amplifier output values that exceed a threshold value, the threshold value being below a maximum amplifier output value;
• and
• generating a thermal image of the target scene based at least on the plurality of amplifier output signals.