Op-Amp Offset Trimming Using SAR Logic and On-Chip Memory
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Solution Overview
Problem
Modern trimming techniques for operational amplifiers face challenges in accurately adjusting parameters such as offset, gain, and temperature drift, often requiring external measurements and complex circuitry, which increases time and cost.
Innovation Solution
A system comprising an operational amplifier integrated circuit chip with a trimming module that utilizes Successive Approximation Register (SAR) logic to adjust operational parameters based on memory values, conducting iterations at different clock cycles to determine coarse and fine bits, allowing for internal trimming without external measurements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If modern trimming techniques use on-chip digital memory and test circuitry to adjust operational parameters, then manufacturing precision is improved, but device complexity increases
Solution Approach 1:
The patent extracts the trimming functionality into a separate, dedicated trimming module that operates independently from the main operational amplifier circuitry. This modular approach allows precise trimming operations to be performed while keeping the main amplifier simple and reducing overall device complexity.
Solution Approach 2:
The trimming module uses the operational amplifier's own output signal to perform self-trimming operations. By feeding the amplifier's output back to the trimming circuitry, the system achieves automatic parameter adjustment without requiring external measurement equipment, thereby reducing device complexity while maintaining high manufacturing precision.
2Measurement precision
If traditional trimming methods use external measurements to determine memory values, then measurement precision is improved, but loss of time increases
Solution Approach 1:
The patent merges the measurement and trimming functions into a single integrated trimming module. The module simultaneously measures the operational amplifier's parameters and adjusts the memory values based on these measurements, eliminating the need for separate external measurement steps and significantly reducing the overall trimming time while maintaining measurement precision.
Solution Approach 2:
The trimming module performs preliminary measurements and adjustments during the manufacturing process before the operational amplifier is deployed. By conducting all necessary measurements and trimming operations in advance using the integrated module, the system achieves precise parameter adjustment without requiring time-consuming external measurements during field operations.
3Manufacturing precision
If trimming module uses multiple iterations at different clock cycle durations to determine memory values, then manufacturing precision is improved, but productivity decreases
Solution Approach 1:
The patent segments the trimming process into multiple phases with different clock cycle durations. Coarse trimming operations use shorter clock cycles for rapid initial adjustment, while fine-tuning operations use longer clock cycles for precise final calibration. This segmentation allows the system to achieve high manufacturing precision without unnecessarily slowing down the entire trimming process, thereby maintaining productivity.
Data Source
AI summary
Disclosed is a system that comprises an operational amplifier with adjustable operational parameters and a trimming module. The trimming module can adjust the operational parameters of the op-amp based on a memory value to compensate for an offset voltage of the op-amp. The trimming module can comprise successive approximation register (SAR) logic that controls the memory value. The SAR logic can be configured to detect a given memory value that causes an output voltage of the op-amp to be within a predetermined voltage interval when applying a predetermined common mode voltage to inverting and non-inverting inputs of the op-amp.