Comparator Circuit Offset Correction via Variable Reference Voltage
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Solution Overview
Problem
Conventional comparator circuits face accuracy issues due to differing input offsets among comparators, which can be exacerbated by environmental changes, and initial correction processes may not adequately address these differences, leading to continued accuracy deterioration.
Innovation Solution
A comparator circuit with a variable reference voltage generating portion and logic portion that adjusts the reference voltage to match the desired output voltage, using a combination of first and second comparators with different characteristics, and performing multiple correction processes to maintain accuracy across varying conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a correction process is performed only when the comparator circuit is activated, then the correction process can be simplified, but input offsets of the comparators may differ from each other due to change in external environment after the correction process
Solution Approach 1:
The patent implements continuous offset correction by repeatedly performing the correction process during both active and inactive periods of the comparator circuit. Specifically, the correction is performed during the inactive period (when switching operation is stopped) and also during specific active periods (when reverse current is detected), ensuring continuous maintenance of accuracy despite environmental changes.
2Ease of operation
If a correction process is performed only when the comparator circuit is activated, then the correction timing is simplified, but inappropriate correction may be performed when it is activated, leading to different input offsets being kept
Solution Approach 1:
The patent performs offset correction in advance during the inactive period (when switching operation is stopped) before the comparator circuit becomes active. This preliminary correction ensures that the comparators are properly calibrated before operation begins, avoiding inappropriate correction during active periods when the circuit is already operating.
Solution Approach 2:
The patent uses reverse current detection as a feedback mechanism to determine when to perform correction during active periods. When reverse current is detected, it indicates a specific operational state, and the correction is performed at this moment to maintain accuracy without disrupting normal operation.
3Adaptability or versatility
If multiple comparators with different characteristics are used, then the comparator circuit can be adapted to different situations, but output accuracy is deteriorated due to different input offsets
Solution Approach 1:
The patent applies different correction strategies to different comparators based on their specific characteristics and operational contexts. Each comparator receives tailored correction during inactive periods and during specific active periods when reverse current is detected, ensuring that each comparator's unique offset characteristics are properly compensated.
Data Source
AI summary
A comparator circuit includes a first comparator, a second comparator, and a logic portion. The logic portion adjust a variable reference voltage input to the second comparator to become close to a reference voltage input to the first comparator, during a period from a time point when reverse current of current flowing in a coil disposed in a switching power supply device is detected in a state where a first comparison signal is output as a comparison signal while the first comparator and the second comparator are operated, until a first predetermined period of time elapses in a state where switching operation of the switching power supply device is stopped (excluding a period from a time point when the reverse current is detected until a second predetermined period of time shorter than the first predetermined period of time elapses).