Current Sense Circuit Offset Compensation in Voltage Regulators
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Solution Overview
Problem
Existing current sense circuits in low dropout (LDO) voltage regulators for portable electronic devices face challenges in accurately monitoring current flow due to internal DC offsets in error amplifiers, leading to errors in power consumption monitoring and optimization.
Innovation Solution
The implementation of a current sense circuit with an error amplifier and offset reduction circuitry that performs two types of offset compensation operations, including sampling mode and chopping, to reduce internal DC offsets and improve the accuracy of current sensing signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a current sense circuit with error amplifier is used to monitor current flow, then current sensing capability is achieved, but DC offsets in the error amplifier cause measurement errors
Solution Approach 1:
The patent implements periodic offset compensation operations including sampling mode and chopping techniques. The error amplifier periodically samples its own offset voltage and subtracts it from the output, effectively eliminating DC offset errors through periodic correction actions rather than continuous offset presence.
Solution Approach 2:
The patent extracts and separates the offset voltage component from the current sensing signal. By using dedicated offset compensation circuitry that specifically targets and removes the DC offset portion, the system isolates the harmful offset component and eliminates it without affecting the useful current measurement signal.
2Measurement precision
If offset compensation operations are implemented to reduce DC offsets, then measurement accuracy is improved, but circuit complexity increases
Solution Approach 1:
The patent merges the offset compensation functionality directly into the existing current sense circuit architecture. The offset compensation operations are integrated with the error amplifier and current sensing path, sharing common components and signal paths where possible, thereby reducing overall circuit complexity compared to having separate independent compensation circuits.
Solution Approach 2:
The error amplifier and current sense circuit perform self-diagnosis and self-correction of their offset errors through automated sampling and chopping operations. The circuit monitors its own offset conditions and automatically compensates without requiring external calibration or manual intervention, reducing the need for additional control circuitry.
Data Source
AI summary
A voltage regulator having current sense capability may include an input node and an output node. A first output device may be electrically connected between the input node and the output node, and configured to control current flow through the first output device to regulate a voltage at the output node. A current sense circuit may be configured to produce a signal that is indicative of the current through the first output device. The current sense circuit may be configured to perform a first kind of offset compensation operation to reduce an offset voltage in an error amplifier of the current sense circuit, and to perform a second kind of offset compensation operation to reduce the offset voltage in the error amplifier.