Regulator Compensation Network for Constant Bandwidth
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Solution Overview
Problem
Conventional regulator circuits face difficulties in maintaining constant bandwidth over a large range of load current, as they are not capable of handling varying load currents from tens of milliamperes to several amperes, including low power standby modes.
Innovation Solution
A regulator circuit with a compensation network that includes a series circuit of a compensation capacitor and a variable resistance circuit, coupled with a current sensing circuit to adjust the resistance based on sensed load current, ensuring stable operation across a wide range of load currents.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a conventional regulator circuit uses a fixed compensation network, then the circuit is simple to design, but the bandwidth varies significantly over a large range of load current
Solution Approach 1:
The patent applies the dynamics principle by replacing the fixed compensation resistor with a variable resistance circuit whose resistance value dynamically adjusts according to the load current. The current sensing circuit detects the load current and controls the variable resistance circuit to provide different compensation values for different operating conditions, enabling the regulator to maintain stable bandwidth from tens of milliamperes to several amperes.
2Ease of manufacture
If the regulator is designed for small load current range, then the compensation is easy to achieve, but the regulator cannot handle large range of load current
Solution Approach 1:
The patent applies parameter changes by modifying the compensation network parameters (resistance value) based on the load current. The variable resistance circuit changes its resistance parameter dynamically - using a higher resistance value for small load currents and a lower resistance value for large load currents. This allows the regulator to maintain proper compensation across the entire load current range from microamperes to amperes.
3Device complexity
If a fixed compensation value is used, then the circuit design is straightforward, but the unit gain bandwidth is not constant over varying load current
Solution Approach 1:
The patent applies feedback by implementing a current sensing circuit that continuously monitors the load current and feeds this information back to the variable resistance circuit. This feedback mechanism allows the compensation network to automatically adjust its resistance value in response to changes in load current, thereby maintaining a constant unit gain bandwidth and ensuring system stability across all operating conditions.
Data Source
AI summary
A linear regulator includes a drive circuit having an input and an output, with the output configured to drive a control terminal of a power transistor for the delivery of a load current. An error amplifier functions to amplify a difference between a reference signal and a feedback signal to generate an error signal at the input of the drive circuit. A compensation circuit includes a series circuit formed by a compensation capacitor and a variable resistance circuit, where the series circuit is coupled to the input of the drive circuit. A current sensing circuit operates to sense the load current. The resistance of the variable resistance circuit is varied in response to the sensed load current.