PWM Signal Measurement Device Using Derivative Analysis
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Solution Overview
Problem
Existing signal processing methods for signals with variable duty cycles and DC offsets are unreliable, as they are sensitive to signal variations, particularly in PWM signals.
Innovation Solution
A method and device that analyze signals by forming the first derivative of incoming square-wave-like signals with variable duty cycles and DC offsets, allowing determination of frequency and duty cycle based on the derivative, using either a differentiating circuit or digital signal processing to offset the influence of DC offsets.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a comparator is used to process PWM signals, then the signal processing is simple, but the processing becomes unreliable when variable DC offset is present
Solution Approach 1:
The patent transforms the signal from the time domain to the frequency domain by taking the first derivative. This parameter transformation allows the system to extract duty cycle information from the amplitude of the derivative signal while being immune to DC offset variations, thus resolving the contradiction between processing simplicity and reliability.
Solution Approach 2:
The first derivative operation serves as an intermediary transformation that converts the original PWM signal into a form where duty cycle information is encoded in the amplitude while DC offset effects are eliminated. This intermediary step enables reliable measurement without requiring complex offset compensation circuits.
2Ease of operation
If traditional methods are used to analyze signals with variable duty cycle and DC offset, then the analysis is straightforward, but the measurement precision deteriorates
Solution Approach 1:
By changing the analysis parameter from direct time-domain voltage measurement to frequency-domain derivative analysis, the system achieves precise duty cycle measurement. The derivative signal's amplitude directly correlates with duty cycle while being independent of DC offset, providing both ease of operation and high measurement precision.
3Reliability
If the first derivative is continuously formed to eliminate DC offset influence, then the measurement reliability improves, but the computational complexity increases
Solution Approach 1:
The patent replaces complex computational methods with a simple analog differentiating circuit that continuously forms the first derivative. This hardware-based approach eliminates the need for complex digital signal processing while maintaining high reliability in duty cycle measurement under varying DC offset conditions.
Data Source
AI summary
The present disclosure provides a method for analyzing a signal, the method comprising receiving an incoming square-wave-like signal that comprises a predetermined frequency and a variable duty cycle, continuously forming the first derivative of the incoming square-wave-like signal, and determining at least one of the frequency, and the duty cycle of the received signal based on the first derivative. Further, the present disclosure provides a measurement application device.