Switching Regulator Control for Fast DVS Without Voltage Overshoot
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Solution Overview
Problem
Conventional switching regulators experience overshoot or undershoot in output voltage during dynamic voltage scaling (DVS), leading to long response times and a trade-off between the severity of these issues and DVS response time, with no effective solution.
Innovation Solution
A switching regulator with a controller circuit that includes a first amplification circuit generating a signal from a low-pass filtered reference signal, a second amplification circuit generating an adjustment signal from a fast response signal, and a ramp signal generation circuit, which compares these signals to produce a PWM signal, adaptively adjusting the amplification or ramp signal to reduce response time and mitigate overshoot or undershoot.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional feedback control is used to regulate output voltage, then voltage stability is maintained, but response time during dynamic voltage scaling increases and overshoot/undershoot occurs
Solution Approach 1:
The feedback control function is segmented into two parallel paths: a first amplification circuit that processes low-pass filtered reference signals for stability, and a second amplification circuit that processes fast response signals for quick voltage adjustments. This segmentation allows simultaneous achievement of voltage stability and fast response time during DVS transitions.
Solution Approach 2:
The controller circuit dynamically switches between different control modes by selecting between the first amplification circuit (for stability) and the second amplification circuit (for fast response) based on the DVS transition state. This dynamic adaptation enables the system to optimize between response time and voltage stability depending on operational requirements.
2Speed
If fast response control is implemented to reduce DVS response time, then response speed improves, but overshoot and undershoot of output voltage worsen
Solution Approach 1:
The control function is divided into two segmented paths: the first amplification circuit with low-pass filtering that ensures voltage accuracy by eliminating high-frequency noise and preventing overshoot, and the second amplification circuit that provides fast response capability. This segmentation resolves the contradiction between speed and accuracy.
Solution Approach 2:
The system changes the bandwidth parameter of the reference signal processing dynamically: using low-pass filtering (narrow bandwidth) in the first amplification circuit to prevent overshoot, and fast response signal processing (wide bandwidth) in the second amplification circuit to achieve quick response. This parameter adaptation resolves the speed-accuracy tradeoff.
Data Source
AI summary
A switching regulator includes a power stage circuit and a controller circuit. The controller circuit includes a first amplification circuit, a second amplification circuit, a ramp signal generation circuit, and a comparator. The first amplification circuit generates an amplification signal according to a difference between a low-pass filtered signal and a feedback signal. The second amplification circuit generates an adjustment signal according to a difference between the feedback signal and a fast response signal. The comparator generates a pulse width modulation signal according to a difference between the amplification signal and a ramp signal to generate a switch control signal. The adjustment signal adaptively adjusts the amplification signal or the ramp signal. The low-pass filtered signal is related to a signal generated by filtering out higher frequency part of the reference signal, and the reference signal is related to a dynamic change of a target level of the output voltage.