Boost Regulator Ripple Injection Circuit
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Solution Overview
Problem
Switching regulators face inefficiency at light load conditions due to insufficient output voltage ripple, which is masked by noise, making it difficult for feedback control loops to operate reliably with low ESR capacitors.
Innovation Solution
A ripple injection circuit is implemented to generate a ripple signal that mimics the actual ripple signal, allowing for stable and enhanced feedback control, even with low or zero ESR output capacitors, by replicating the charge delivered to the output capacitor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If low ESR capacitors are used to reduce output voltage ripple, then efficiency and output voltage ripple are improved, but feedback control loop operation becomes unreliable due to insufficient ripple signal
Solution Approach 1:
A ripple injection circuit is introduced as an intermediary component that generates an artificial ripple signal to supplement the insufficient natural ripple from low ESR capacitors. This mediator provides the feedback control loop with adequate ripple information without requiring high ESR capacitors, thus maintaining both efficiency and reliability.
Solution Approach 2:
The invention changes the parameter of output voltage ripple by injecting an additional ripple signal through the ripple injection circuit. This modifies the total ripple characteristics at the feedback node, ensuring sufficient ripple amplitude for reliable control loop operation while allowing the use of low ESR capacitors for improved efficiency.
2Loss of energy
If PFM control is used to improve efficiency at light load, then switching losses are reduced, but multi-pulsing and chattering occur due to insufficient ripple signal
Solution Approach 1:
The ripple injection circuit acts as a mediator that provides sufficient ripple signal to the PFM control loop, preventing multi-pulsing and chattering phenomena. This enables stable light load operation while maintaining the efficiency benefits of PFM control.
Solution Approach 2:
By injecting an additional ripple signal, the invention changes the effective ripple parameter seen by the PFM control loop. This ensures the control loop operates reliably across all load conditions, eliminating instability issues at light load while preserving switching loss reductions.
3Ease of operation
If output voltage ripple is reduced using low ESR capacitors, then output voltage quality is improved, but feedback control becomes difficult due to noise masking
Solution Approach 1:
The ripple injection circuit serves as an intermediary that generates a distinct artificial ripple signal which is easier to detect than the微弱 natural ripple from low ESR capacitors. This mediator signal rises above the noise floor, making ripple detection and feedback control significantly easier while maintaining high output voltage quality.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This solution ensures optimal ripple injection for the feedback control loop, reducing multi-pulsing and chattering, and maintaining efficient operation across varying load conditions, even with low ESR capacitors, by providing a sufficient ripple signal for regulation.
Implementation Method 1
A power switch is turned on to apply energy to an inductor to allow the current through the inductor to build up. When the power switch is turned off, the voltage across the inductor reverses and energy is transferred to an output capacitor and the load.
Implementation Method 2
The output capacitor COuT filters the ramping inductor current to generate a substantially constant output voltage VOUT at the output node 16.
Data Source
AI summary
A boost switching regulator incorporates a peak inductor current modulation circuit to modulate the peak inductor current as a function of the load current, the input voltage, the regulated output voltage, and a fixed current value. In this manner, the switching frequency of the boost regulator can be maintained above a given value or within a given frequency range over a wide range of load conditions and also over input voltage variations and output voltage settings.