Feed-forward Compensation for Hysteretic Switching Regulator DC Errors
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Solution Overview
Problem
Hysteretic switching regulators face errors in output voltage due to unknown duty-cycles and variations in external components, leading to DC errors in the feed-forward ramp voltage relative to the feedback voltage, which affect the accuracy of the output voltage.
Innovation Solution
A feed-forward compensation stage is introduced to measure the DC error of the feed-forward ramp voltage and generate a compensation voltage that cancels out the error by combining it with the feedback voltage or reference voltage, ensuring accurate output voltage regulation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a hysteretic switching regulator is configured without an error amplifier to achieve fast transient response, then the dynamic power delivery characteristics are improved, but DC errors in the output voltage occur due to unknown duty-cycles and component variations
Solution Approach 1:
The patent implements a feed-forward compensation mechanism that uses feedback from the output voltage to generate a compensation signal. This compensation signal is added to the reference voltage to counteract DC errors, thereby maintaining output voltage accuracy while preserving the fast transient response characteristics of the hysteretic regulator
Solution Approach 2:
The patent dynamically adjusts the reference voltage parameter by adding a compensation voltage that is derived from the output voltage feedback. This parameter change allows the system to correct DC errors caused by duty-cycle variations and component tolerances, improving output voltage accuracy without sacrificing speed
2Productivity
If feed-forward ramp voltage is added to feedback voltage to set control signal frequency, then the switching frequency is stabilized, but DC errors in the feed-forward ramp voltage relative to feedback voltage cause output voltage inaccuracies
Solution Approach 1:
The patent uses feedback from the output voltage to generate a compensation signal that counteracts DC errors in the feed-forward ramp voltage. This feedback mechanism maintains both frequency stability and voltage accuracy by dynamically adjusting the reference voltage based on actual output conditions
Solution Approach 2:
The patent introduces a compensation voltage as an intermediary element between the feed-forward ramp voltage and the feedback voltage. This compensation voltage acts as a mediator that cancels out DC errors, allowing the feed-forward mechanism to maintain frequency stability while preventing accuracy degradation
Data Source
AI summary
One embodiment of the invention includes a hysteretic power regulator system. The system includes a switching stage configured to periodically couple an input voltage to an inductor in response to a control signal to generate an output voltage. The system also includes a hysteretic control stage configured to generate the control signal based on a comparison of a feedback voltage associated with the output voltage and a predetermined reference voltage. The system also includes a feed-forward stage configured to generate a feed-forward ramp voltage in response to the control signal. The feed-forward ramp voltage can be added to the feedback voltage to set a frequency of the control signal. The system further includes a compensation stage configured to cancel a DC error associated with the feed-forward ramp voltage relative to the feedback voltage to substantially mitigate errors associated with the output voltage.