Constant On-Time Buck Control With Ripple-Injected Feedback
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Solution Overview
Problem
Power supplies for electronic circuits often produce voltages that are higher than required, leading to inefficiencies and instability, particularly in mobile electronics where buck converters are used to regulate these voltages but face challenges in managing ripple noise and transient fluctuations.
Innovation Solution
A buck converter employing constant-on-time control with a ripple injector that integrates ripple information with DC feedback to stabilize output voltage, using a control circuit that compares error signals with feedback signals to adjust switching duty cycles, thereby reducing jitter and improving DC regulation and transient response.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional voltage regulation methods are used, then output voltage can be controlled, but ripple noise and transient fluctuations increase
Solution Approach 1:
The feedback signal is segmented into two separate paths: one path processes the DC component of the output voltage through an error amplifier, while the other path processes the AC ripple component through a ripple injector. This segmentation allows independent optimization of DC regulation and ripple suppression, resolving the contradiction by handling each component through dedicated circuitry rather than a single feedback path.
Solution Approach 2:
A ripple injector circuit is introduced as an intermediary component that adds a scaled version of the ripple signal back into the feedback path. This intermediary element compensates for the harmful ripple effects by counteracting them with an equal and opposite signal, thereby reducing overall ripple noise while maintaining stable DC output voltage.
2Power
If high input voltages are used, then power delivery capability increases, but DC regulation and transient response deteriorate
Solution Approach 1:
The patent implements a dual-loop feedback system where the DC feedback path continuously monitors and adjusts the output voltage to maintain precise DC regulation, while the ripple feedback path separately handles transient fluctuations. This enhanced feedback mechanism allows the system to maintain excellent DC regulation even when operating with high input voltages that would otherwise cause instability.
3Speed
If switching frequency is increased, then transient response improves, but ripple noise and jitter increase
Solution Approach 1:
The control system dynamically adjusts the switching duty cycle based on real-time feedback from both DC and ripple monitoring paths. This dynamic control allows the system to respond quickly to transient changes (improving transient response) while simultaneously suppressing ripple and jitter through active compensation, resolving the contradiction between speed and harmful factors.
Data Source
AI summary
A switching power supply employs constant-on-time control to maintain an output-voltage signal across a load. The output-voltage signal includes DC and ripple components. An error amplifier issues an error signal responsive to deviations between the DC component and a reference. A ripple injector integrates the DC and ripple components into a feedback signal. A constant on-time control circuit uses both the error signal and the integrated feedback signal to suppress transient DC fluctuations of the output voltage and improve DC regulation.