US 2019/0368941 A1 · LOW COST AND HIGH PERFORMANCE BOLOMETER CIRCUITRY AND METHODS

Abstract

A bolometer circuit may include an active bolometer configured to receive external infrared (IR) radiation. The bolometer circuit may be configured to reduce power consumption at high temperatures. In particular, the bolometer circuit may include additional resistors provided in the resistive loads for bolometer conduction paths to limit power at high temperatures. In some embodiments, the bias (e.g., a voltage level) to the gates of transistors in the resistive loads for the bolometer conduction paths may be adjusted based on temperature to limit power and/or current at high temperatures. In bolometer circuits with a feedback resistor provided across an amplifier to configure a feedback amplifier, a circuit with adjustable amplifier power may be provided to save power. In some embodiments, a bolometer circuits may be provided with reduced gains to allow for very hot scenes to be imaged without railing the output.

Claims20

Dependent claims

A bolometer circuit comprising:

a substrate;
an active bolometer configured to receive external infrared (IR) radiation and substantially thermally isolated from the substrate;
and
a thermally shorted bolometer and a transistor configured to be connected in series with the active bolometer in a bolometer conduction path from a supply voltage node to a common voltage node, the transistor operating as a current source that generates a load current to the active bolometer and the thermally shorted bolometer thermally shorted to the substrate to operate as a temperature-compensated load for the bolometer conduction path,
wherein the bolometer circuit is configured to limit the load current and reduce power consumption when an ambient temperature is elevated.

2 more elements

A bolometer circuit comprising:

a substrate;
an active bolometer configured to receive external infrared (IR) radiation and substantially thermally isolated from the substrate;
a resistive load, wherein the active bolometer and the resistive load are configured to be connected in series in a bolometer conduction path from a supply voltage node to a common voltage node;
an amplifier circuit configured to provide an adjustable gain setting, the amplifier circuit comprising:
an operational amplifier (op-amp) having a first input coupled to a node in the bolometer conduction path between the resistive load and the active bolometer;
a resistive gain coupling an output of the op-amp to the first input of the op-amp;
and
an amplifier power control circuit configured to adjust a current supplied to the op-amp based on an ambient temperature and/or the adjustable gain setting;
and
a voltage source coupled to a second input of the op-amp to provide a reference voltage level,
wherein the amplifier circuit is configured to generate a current flow through the resistive gain in response to a resistance change of the active bolometer due to the external IR radiation at least by maintaining the reference voltage level at the first input of the op-amp, and
wherein the amplifier circuit is further configured to convert the current flow into an output voltage at the output of the op-amp that is indicative of an intensity of the external IR radiation received at the active bolometer.

9 more elements

A bolometer circuit comprising:

a substrate;
an active bolometer configured to receive external infrared (IR) radiation and substantially thermally isolated from the substrate;
a resistive load, wherein the active bolometer and the resistive load are configured to be connected in series in a bolometer conduction path from a supply voltage node to a common voltage node;
an amplifier circuit comprising:
an operational amplifier (op-amp) having a first input coupled to a node in the bolometer conduction path between the resistive load and the active bolometer and a second input configured to receive a reference voltage level;
a resistive gain coupling an output of the op-amp to the first input of the op-amp;
and
a first and a second thermally shorted bolometers thermally shorted to the substrate,
wherein the first thermally shorted bolometer is configured to be connected in series with the active bolometer to the common voltage node and having approximately N times the resistance of the active bolometer,
wherein the second thermally shorted bolometer is configured to be connected in parallel with the active bolometer to the common voltage node and having approximately (N+1)/N times the resistance of the active bolometer, and
wherein a bias voltage across the active bolometer is reduced and a distribution of bias voltages at the node in the bolometer conduction path between the resistive load and the active bolometer is not substantially altered by connecting the first and the second thermally shorted bolometers in series and in parallel, respectively, to the active bolometer.

8 more elements

Dependencies are inferred from the claim text.

Low cost and high performance bolometer circuitry and methods

Life of this patent

Low cost and high performance bolometer circuitry and methods

Life of this patent

Abstract

Claims20