Mixed-Signal Analog Auto-Calibration for Input Offset Compensation
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Solution Overview
Problem
Integrated circuits with analog input devices face challenges in minimizing input offset voltage, which requires costly factory calibration and is not adaptable to changing environmental conditions, limiting their effectiveness and increasing production costs.
Innovation Solution
An auto-calibration circuit that allows for on-demand calibration of analog input devices using a digital control circuit, external voltage calibration, and compensation mechanisms to adjust for input offset voltage, enabling compensation during end-user application and reducing the need for factory calibration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If factory calibration is performed to minimize input offset voltage, then manufacturing precision is improved, but production time increases and production cost increases
Solution Approach 1:
The patent implements self-calibration capability within the analog input device itself, allowing the device to automatically minimize its own input offset voltage without requiring external factory calibration equipment. The device uses internal circuitry to perform calibration operations autonomously, eliminating the need for specialized factory testing equipment and reducing production time while maintaining manufacturing precision.
Solution Approach 2:
The patent performs calibration operations during the manufacturing process as a preliminary action, storing calibration data in non-volatile memory. This preliminary calibration captures the offset characteristics at factory, and the stored data is used during normal operation to compensate for offset voltage, thereby avoiding the need for repeated calibration and reducing overall production time.
2Manufacturing precision
If factory calibration is performed at one operating point, then manufacturing precision is improved, but adaptability to changing environmental conditions deteriorates
Solution Approach 1:
The patent implements a feedback mechanism that continuously monitors the analog input device's performance during operation and automatically adjusts calibration parameters to compensate for environmental changes. The system uses the stored calibration data and real-time measurements to maintain accurate offset compensation across varying temperature, voltage, and other operating conditions, thereby improving adaptability while maintaining manufacturing precision.
Solution Approach 2:
The patent transitions from static factory calibration to dynamic self-calibration that adapts to changing operating conditions. The calibration system can be re-triggered during operation based on detected events such as temperature changes or voltage variations, allowing the device to dynamically adjust its offset compensation and maintain manufacturing precision across different environmental conditions.
3Manufacturing precision
If separate testing equipment is used for digital and analog functions, then manufacturing precision is improved, but device complexity and production cost increase
Solution Approach 1:
The patent merges the calibration functionality into the analog input device itself, combining what would traditionally require separate factory testing equipment with the device's internal operations. By implementing self-calibration circuitry within the analog device, the patent eliminates the need for separate external calibration equipment, reducing overall system complexity while maintaining the precision needed for accurate offset voltage minimization.
Data Source
AI summary
Auto-calibration of the analog circuits occurs when requested by a user and/or the occurrence of an event(s). The user may invoke an auto-calibration on demand through an auto-calibration (ACAL) input to the mixed-signal integrated circuit. An external voltage calibration (VCAL) input may be used for auto-calibration of the mixed-signal integrated circuit to a user-supplied common-mode voltage reference. Auto-calibration of the mixed-signal integrated circuit may also be initiated upon the occurrence of any one or more of the following events: 1) detection of auto-calibration data corruption, e.g., parity checking of auto-calibration data values digitally stored in the mixed-signal integrated circuit; 2) an internal timer that causes a calibration request after a programmable timeout period, 3) change in the internal integrated circuit die temperature as determined by a temperature sensor, and 4) a change in the power supply and/or internal supply voltage(s).