Voltage Regulator High Duty Cycle Linearity
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Solution Overview
Problem
Hysteretic regulators used in mobile devices experience significant output voltage ripple in operation regions with high duty cycles, which is unsuitable for devices requiring low power consumption and fast voltage transient response.
Innovation Solution
A voltage regulator design incorporating a high duty cycle detector, feedback controller, hysteretic comparator, first driver, low pass filter, and second driver, which generates high linearity between reference and output voltages, prevents reverse and overcurrents by activating appropriate feedback voltages and drivers based on duty cycle signals, ensuring fast transient response without ripple.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If a hysteretic regulator is used to achieve low power consumption and fast voltage transient response, then power efficiency and response speed are improved, but output voltage ripple increases significantly in high duty cycle operation regions
Solution Approach 1:
The voltage regulator is segmented into two parallel paths: a first voltage regulator (hysteretic regulator) for normal operation and a second voltage regulator (linear regulator) for high duty cycle conditions. The controller selectively activates the appropriate path based on duty cycle detection, allowing each segment to operate in its optimal regime without the drawbacks of the other.
Solution Approach 2:
The system dynamically changes its operating parameters by switching between two different regulation mechanisms based on the duty cycle parameter. When the duty cycle exceeds a threshold, the controller transitions from hysteretic regulation to linear regulation, effectively changing the control parameter to maintain low ripple while preserving fast response capability.
2Loss of energy
If the input voltage and output voltage are close together (high duty cycle region), then voltage regulation efficiency is improved, but output voltage ripple increases significantly
Solution Approach 1:
The voltage regulator employs dynamic switching between two regulation modes based on real-time duty cycle conditions. The controller continuously monitors the duty cycle and dynamically transitions between hysteretic and linear regulation, allowing the system to adapt its behavior to maintain low ripple whenever the input-output voltage differential is small.
Solution Approach 2:
The controller acts as an intermediary that monitors duty cycle conditions and selectively engages the second voltage regulator (linear regulator) as a mediator to suppress ripple when the first regulator (hysteretic regulator) would otherwise produce excessive ripple in high duty cycle conditions.
3Speed
If a switching regulator is used to provide rapid input voltage changes for RF power amplifiers, then voltage transient response is improved, but power consumption increases
Solution Approach 1:
The power supply system is segmented into a hysteretic regulator path for fast transient response and a linear regulator path for low power consumption during steady-state operation. This segmentation allows the system to leverage the speed advantage of switching regulation only when necessary, while using efficient linear regulation during normal operation.
Solution Approach 2:
The controller employs periodic duty cycle monitoring and selective activation of the second voltage regulator to maintain low ripple during high duty cycle periods while allowing the first regulator to handle transient conditions, creating a periodic switching pattern that balances speed and efficiency requirements.
Data Source
AI summary
A voltage regulator includes a high duty cycle detector, a feedback controller, a hysteretic comparator, and first and second drivers. The high duty cycle detector generates a high duty cycle signal based on a power supply voltage and a reference voltage. The feedback controller generates first and second feedback voltages based on the reference voltage, the high duty cycle signal and an output voltage of the voltage regulator. The hysteretic comparator compares the reference voltage and the first feedback voltage to generate a control signal. When the first feedback voltage is activated, the first driver drives an output node that provides the output voltage based on the control signal and the high duty cycle signal. When the second feedback voltage is activated, the second driver generates a third voltage proportional to the reference voltage based on the power supply voltage and the second feedback voltage, and drives the output node with the third voltage.