Op-Amp Offset Correction Circuit for Varying Operating Conditions
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Solution Overview
Problem
Existing methods for correcting input offset voltage in operational amplifiers are inadequate, as they either require additional circuitry, leading to increased costs and reduced performance under varying operating conditions, or result in significant errors due to the inability to accurately minimize input offset voltage across different conditions.
Innovation Solution
A micro control unit is used to control a register and switch circuit, allowing the operational amplifier to switch between normal and offset voltage correcting modes, utilizing an offset voltage correction unit with increased correction bits to minimize input offset voltage effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If trimming method is used to correct input offset voltage, then input offset voltage is minimized under correct conditions, but performance deteriorates under varying operating conditions
Solution Approach 1:
The patent implements a dynamic correction system that automatically adjusts the correction amount based on real-time detection of operating conditions. The micro control unit monitors parameters such as operating voltage, temperature, and input voltage, and dynamically modifies the correction applied to the input offset voltage, enabling the system to adapt to varying conditions rather than relying on fixed trimming values
Solution Approach 2:
The system employs a feedback mechanism where the micro control unit continuously detects operating conditions and the actual input offset voltage, then adjusts the correction amount accordingly. This closed-loop feedback ensures that the correction remains accurate across different operating conditions by constantly monitoring and adjusting based on actual system state
2Measurement precision
If chopper method is adopted to correct input offset voltage, then circuit complexity increases with additional clock circuit and filter, but input offset voltage correction is improved
Solution Approach 1:
The patent introduces a micro control unit as an intermediary component that digitally processes offset voltage correction. Instead of using complex analog chopper circuits with clock signals and filters, the micro control unit reads correction values from a register and applies digital correction, simplifying the circuit architecture while maintaining or improving correction accuracy
Solution Approach 2:
The patent replaces the mechanical/analog chopper method with a digital control approach. The micro control unit and register system substitute for the complex analog clock circuit and filter components, achieving offset voltage correction through digital means rather than analog signal modulation, thereby reducing circuit complexity
3Ease of manufacture
If trimming method is used for input offset voltage correction, then manufacturing cost is reduced, but correction accuracy varies with operating conditions
Solution Approach 1:
The patent performs preliminary trimming during the manufacturing process to establish a baseline correction value, then stores this value in a register. The micro control unit later adjusts this pre-established correction based on detected operating conditions, combining the cost-effectiveness of manufacturing-time trimming with the adaptability of runtime adjustment
Solution Approach 2:
The system changes the correction parameter dynamically based on operating conditions. The micro control unit modifies the correction amount stored in or derived from the register based on detected parameters such as temperature and operating voltage, allowing the system to maintain accuracy across different conditions while using a simple register-based storage mechanism
Data Source
AI summary
An input offset voltage corrector used in an operational amplifier includes a switch unit, a register unit, an offset voltage correction unit and a micro control unit. The micro control unit sets the register unit to control the switch unit to switch the input offset voltage corrector to different operating modes. If an input offset voltage corrector is set to the offset voltage correcting mode, the offset voltage correction unit will adjust the input offset voltage of the operational amplifier to output an exact signal. Furthermore, the input offset voltage corrector can adjust the input offset voltage anytime according to the operating conditions to maintain the best characteristic of the operational amplifier.