PCB Differential Feedback Traces for Stable Power Supply Sampling
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Solution Overview
Problem
Existing power supply circuits face accuracy issues in voltage sampling when load current is high, leading to instability in load terminal voltage due to significant voltage differences between input and output terminals, which affects the normal operation of power supply devices.
Innovation Solution
A power supply circuit design that includes a processing circuit, load circuit, and feedback circuit connected in a differential trace manner, with a differential circuit and capacitors to directly obtain the output terminal voltage and generate accurate sampling values, thereby improving voltage stability and accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If voltage sampling is performed after a filter circuit when load current is large, then the power supply circuit can handle high load currents, but the accuracy of the sampling value deteriorates due to great voltage difference between input and output terminals
Solution Approach 1:
A differential circuit is introduced as an intermediary between the filter circuit output and the feedback circuit input. The differential circuit includes a differential trace with equal-length first and second differential wires, where the first differential wire connects the filter circuit output to the feedback circuit, and the second differential wire provides a reference path. This intermediary structure compensates for voltage drops and maintains sampling accuracy even when handling high load currents.
Solution Approach 2:
The patent transitions from single-ended voltage sampling to differential voltage sampling by introducing a second differential wire that runs parallel to the first differential wire. This creates a differential signal path that measures voltage difference rather than absolute voltage, effectively eliminating the impact of common-mode voltage drops caused by high load currents on sampling accuracy.
2Measurement precision
If the feedback circuit is directly connected to the load circuit output terminal, then the sampling value accuracy improves, but the circuit complexity increases due to additional differential circuit components
Solution Approach 1:
The patent changes the electrical parameters of the connection by using a differential trace structure with controlled impedance and equal-length routing. Instead of a simple direct connection, the differential circuit maintains specific electrical characteristics (equal length, differential signaling) that provide immunity to noise and voltage drops while keeping the overall circuit design systematic and manageable.
3Reliability
If a differential trace is used to connect the load circuit and feedback circuit, then the anti-interference capability improves, but the PCB layout complexity increases
Solution Approach 1:
The differential trace design ensures that the first and second differential wires have equal lengths and are routed symmetrically on the PCB. This equipotential approach ensures that both wires experience identical electromagnetic interference and voltage drops, allowing the differential signaling to reject common-mode noise and maintain signal integrity despite the increased layout requirements.
Data Source
AI summary
This application includes a power supply circuit, a PCB circuit board, a power supply device. The power supply circuit includes a processing circuit, a load circuit and a feedback circuit which are sequentially connected. The feedback circuit is connected to an output terminal of the load circuit and an input terminal of the processing circuit, and is configured to obtain a voltage of the output terminal of the load circuit and generate a sampling value. The processing circuit is configured to control a voltage of the output terminal of the load circuit according to the sampling value. The power supply circuit includes a differential circuit which connects the load circuit and the feedback circuit by using a differential trace manner. By means of differential trace manner, accuracy of an obtained sampling value is improved and a stability of a voltage of the output terminal of the load circuit is ensured.