On-chip bias calibration for microbolometer readout circuits
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Solution Overview
Problem
The integration of microbolometer-based imaging sensors with cameras requires complex calibration processes that introduce additional components and design complexity due to non-uniform voltage outputs across pixel arrays, complicating the interaction and communication between devices.
Innovation Solution
An on-chip readout circuit assembly for microbolometer focal plane arrays that includes a memory for storing biasing values, a column readout for searching and applying bias adjustments, and a column multiplexer for dynamic column selection, enabling self-calibration of bias values to achieve uniform output voltages.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If microbolometer-based imaging sensors are integrated with cameras, then imaging functionality is achieved, but design complexity and component count increase due to required calibration processes
Solution Approach 1:
The patent merges the calibration functionality into the readout integrated circuit (ROIC) by integrating a memory device and calibration circuitry directly with the pixel array. This combines multiple functions (detection, reading, and calibration) into a single integrated device, eliminating the need for separate calibration components and reducing overall system complexity.
Solution Approach 2:
The microbolometer detector performs self-calibration through on-chip bias calibration. The integrated memory stores bias values for each pixel, and the calibration circuit automatically adjusts bias voltages without requiring external calibration equipment or complex communication protocols, enabling the system to calibrate itself.
2Measurement precision
If external calibration components and communication protocols are used, then pixel calibration is achieved, but component count and design complexity increase
Solution Approach 1:
The calibration memory and readout circuitry are merged into a single integrated circuit chip. The memory device is directly coupled to the pixel array, and the same circuit that reads pixel signals also performs calibration, eliminating the need for separate external calibration components.
Solution Approach 2:
The readout integrated circuit serves multiple functions: it reads pixel signals during normal operation and performs bias calibration during calibration mode. The same hardware infrastructure is used for both detection and calibration, making the system multi-functional without requiring additional dedicated calibration components.
Data Source
AI summary
A readout circuit that allows on-chip bias calibration of a microbolometer focal plane array (FPA). The readout circuit includes a memory for storing one or more biasing values for a plurality of pixels within the FPA, the plurality of pixels being arranged in one or more columns and one or more rows within the FPA. The readout circuit further includes a column readout connected to the memory and configured to search for the one or more biasing values and to apply a bias adjustment based on the one or more biasing values to a signal received from the FPA. The readout circuit further includes a column multiplexer connected to the column readout and configured to perform dynamic column selection for one or more columns of pixels within the FPA.