Shared Amplifier Offset Compensation for Accurate Low-Area Circuits
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Solution Overview
Problem
Conventional methods for correcting input referred offset voltage in operational amplifiers are inefficient, leading to amplification errors and increased complexity, space consumption, and design costs due to the need for large resistor chains, auxiliary amplifiers, and dedicated clock circuits.
Innovation Solution
A system comprising a first and second amplifier, a compensation-setting generator, and controllers that apply generated compensation settings to each amplifier to continuously correct input referred offset voltage, using a single compensation-setting generator to update settings in different time slots, reducing the need for multiple offset correction circuits and simplifying design.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional methods (large resistor chain and iDAC) are used to minimize input referred offset, then offset accuracy is improved, but space consumption increases and manufacturing cost increases due to trim process
Solution Approach 1:
The patent combines multiple offset correction functions into a single shared compensator that serves multiple amplifiers. The compensator generates compensation signals that are distributed to different amplifiers through switching circuitry, eliminating the need for separate correction circuits for each amplifier and reducing overall space consumption
Solution Approach 2:
The shared compensator is designed to provide offset correction for multiple amplifiers simultaneously or sequentially. A single compensator circuit can generate compensation signals that are applicable to different amplifiers, making the correction mechanism universal and reducing the total component count
2Measurement precision
If auxiliary amplifier is used to sensing/correcting input referred offset voltage, then offset correction capability is improved, but space consumption increases and design complexity increases due to dedicated clock circuit requirements
Solution Approach 1:
The patent merges the offset correction function into the main amplifier structure or shares it among multiple amplifiers, eliminating the need for separate auxiliary amplifiers. The compensation is achieved through integrated circuitry that works in conjunction with the existing amplifier stages, reducing overall system complexity
Solution Approach 2:
The amplifier system performs its own offset correction through integrated compensation circuitry that is part of the amplifier structure. The system uses its own resources and existing components to generate and apply compensation signals, eliminating the need for external auxiliary amplifiers and dedicated control circuits
3Measurement precision
If chopping method is used to correct input referred offset, then offset accuracy is improved, but circuit complexity increases due to polarity switching requirements and filter design
Solution Approach 1:
The patent employs periodic switching of the compensation signal polarity or injection timing to achieve offset cancellation. By periodically modulating the compensation signal and using switching circuitry to alternate its application, the system can cancel offset errors without requiring complex continuous modulation schemes or additional filtering stages
Data Source
AI summary
An apparatus includes a first amplifier, a second amplifier, and a compensation-setting generator to generate a first amplifier compensation setting and second amplifier compensation setting. A controller is operable to: i) apply the first amplifier compensation setting to the first amplifier and apply the second amplifier compensation setting to the second amplifier. The controller is further operable to switch between generating updates to the first amplifier compensation setting and the second amplifier compensation setting.