Integrator Circuit Calibration with Trimmable Time-Constant Control
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Solution Overview
Problem
On-chip integrator circuits suffer from inaccuracies due to process variation, leading to a +/-25% variation in time constant, which affects the output accuracy.
Innovation Solution
Incorporation of a trimmable component and a calibration control circuit to adjust the control signal based on a comparison of the ramp time to a target time constant, ensuring precise calibration of the integrator circuit.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If standard IC components are used in the integrator circuit, then the circuit can be manufactured with standard processes, but the time constant varies by +/-25% due to process variation
Solution Approach 1:
The patent implements a trimmable capacitor that can dynamically adjust its capacitance value after manufacturing. The capacitor includes multiple capacitive elements that can be selectively connected or disconnected through control signals, allowing the time constant to be trimmed to compensate for process variations while maintaining standard manufacturing processes.
Solution Approach 2:
The patent changes the electrical parameter (capacitance) of the capacitor by selectively activating different capacitive elements. This allows the time constant to be adjusted within a range to compensate for manufacturing variations, resolving the contradiction between ease of manufacture and manufacturing precision.
2Manufacturing precision
If a trimmable component is added to adjust the time constant, then the time constant accuracy is improved, but the circuit complexity increases
Solution Approach 1:
The capacitor is segmented into multiple discrete capacitive elements (first capacitive element, second capacitive element, etc.) that can be independently controlled. This segmentation allows precise adjustment of the time constant by selectively connecting or disconnecting individual elements, achieving accurate trimming without requiring a completely redesign of the capacitor structure.
Solution Approach 2:
The calibration control circuit serves multiple functions: it measures the actual time constant, compares it with the target value, and generates control signals to adjust the trimmable capacitor. This multi-functional approach reduces the need for separate calibration equipment and simplifies the overall system complexity.
3Measurement precision
If calibration operations are performed to adjust the trimmable component, then the output accuracy is improved, but the calibration time is added
Solution Approach 1:
The patent performs calibration operations during the manufacturing or initialization phase before the integrator circuit is put into normal operation. The calibration control circuit measures the actual time constant and adjusts the trimmable capacitor to match the target value in advance, ensuring accurate output without adding calibration time during operational use.
Solution Approach 2:
The calibration control circuit implements a feedback mechanism by measuring the actual time constant, comparing it with the target value, and using the comparison result to generate control signals that adjust the trimmable capacitor. This closed-loop feedback ensures accurate calibration while minimizing the number of adjustment iterations required, thereby reducing calibration time.
Data Source
AI summary
A circuit includes an integrator circuit. The integrator circuit includes: an operational amplifier having an input terminal and an output terminal; a trimmable component having a first terminal, a second terminal, and a control terminal, the first terminal of the trimmable component coupled to the input terminal, and the second terminal of the trimmable component coupled to the output terminal; and a calibration control circuit having a first terminal and a second terminal, the first terminal of the calibration control circuit coupled to the output terminal, and the second terminal of the calibration control circuit coupled to the control terminal of the trimmable component.