Switching Signal Delay Reduces Noise in Multi-Inductor Power Supplies
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Solution Overview
Problem
Switching power supplies using inductive elements face a trade-off between higher inductances that reduce ripple currents and lower inductances that increase slew rates, leading to noise in power supply output signals due to ripple currents.
Innovation Solution
The implementation of a power supply switching circuitry with two inductive elements, where the second switching output signal is delayed from the first, creating a combined inductor current with frequency notches that can be adjusted to reduce noise at targeted frequencies by selecting the switching signal delay.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If higher inductances are used in the inductive elements, then ripple currents are reduced, but slew rates of the power supply output signals are reduced
Solution Approach 1:
The patent divides the single inductive element into multiple parallel inductive elements (first inductive element and second inductive element). Each inductive element operates with its own switching signal, allowing the system to achieve lower equivalent inductance while maintaining ripple current reduction through proper phase management of the switching signals.
Solution Approach 2:
The patent employs periodic switching signals with controlled phase differences to drive the multiple inductive elements. By adjusting the phase difference between switching signals, the system creates frequency notches at specific frequencies, enabling targeted ripple current reduction while maintaining high slew rates through the combined effect of multiple inductors.
2Speed
If lower inductances are used in the inductive elements, then slew rates of the power supply output signals are increased, but ripple currents increase leading to noise in the power supply output signal
Solution Approach 1:
The patent segments the inductive load into multiple parallel inductors, each contributing to the overall current output. This segmentation allows the use of lower individual inductance values to maintain high slew rates, while the combined parallel configuration and phase-controlled switching reduce the amplitude of ripple currents and resulting noise.
Solution Approach 2:
The patent converts the harmful ripple currents generated by lower inductance values into a beneficial effect by using phase-controlled switching to create frequency notches. The ripple currents at specific frequencies are suppressed through constructive and destructive interference patterns, transforming the noise problem into a targeted frequency filtering mechanism.
3Device complexity
If a single inductive element is used, then the circuit complexity is reduced, but the ability to reduce noise at targeted frequencies is limited
Solution Approach 1:
The patent introduces multiple inductive elements with associated switching signals, creating a segmented architecture that enables frequency-selective noise reduction. The segmentation allows independent control of each inductor's switching phase, creating frequency notches at specific frequencies while maintaining manageable circuit complexity through systematic design.
Solution Approach 2:
The patent changes the switching parameters (phase differences, duty cycles) of the multiple inductive elements to create frequency notches at targeted frequencies. By adjusting these parameters, the system can dynamically suppress noise at specific frequencies without requiring complex additional filtering components, maintaining relatively simple circuit architecture.
Data Source
AI summary
Embodiments of circuitry, which includes power supply switching circuitry, a first inductive element, and a second inductive element, are disclosed. The power supply switching circuitry provides a first switching output signal to the first inductive element and a second switching output signal to the second inductive element. The first inductive element has a first inductor current and the second inductive element has a second inductor current. The second switching output signal is delayed from the first switching output signal by a switching signal delay. The first inductor current and the second inductor current combine to provide a combined inductor current, which has a frequency response with a group of notches, such that frequency locations of the group of notches are based on the switching signal delay.