PWM Reference Signal Shaping for Lower DA Converter Sampling
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The high cost of DA converters used in pulse width modulation systems is due to the high sampling frequency required for generating triangular wave signals, which increases the overall cost of the system.
Innovation Solution
A signal modulation apparatus and method that generate an analog reference signal by removing higher-order harmonic components from a triangular wave signal, perform pulse width modulation using this reference signal, and apply nonlinear conversion to reduce errors, thereby reducing the sampling frequency and cost of DA converters.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a triangular wave signal is used for pulse width modulation, then the modulation function is achieved, but the sampling frequency of the DA converter must be high, increasing cost
Solution Approach 1:
The patent extracts and removes higher-order harmonic components from the triangular wave signal, keeping only the fundamental frequency component. This extraction process allows the system to achieve adequate modulation performance with a lower sampling frequency, thereby reducing DA converter cost while maintaining essential modulation functionality.
Solution Approach 2:
The patent changes the frequency spectrum parameters of the triangular wave signal by filtering out higher-order harmonics. This parameter modification reduces the required sampling frequency according to the Nyquist criterion, enabling the use of lower-cost DA converters that operate at reduced sampling rates while still achieving the necessary modulation performance.
2Ease of manufacture
If higher-order harmonic components are removed from triangular wave signal, then the sampling frequency can be reduced, but signal accuracy may be degraded
Solution Approach 1:
The patent applies feedback through a nonlinear converter that processes the PWM output signal and feeds back correction information to compensate for the distortion caused by harmonic removal. This feedback mechanism restores signal accuracy by correcting the waveform deviations introduced by filtering out higher-order components, thereby maintaining measurement precision while allowing reduced sampling frequency.
Solution Approach 2:
The patent combines multiple processing stages - linear filtering to remove harmonics, PWM modulation, and nonlinear conversion with feedback - to create a composite signal processing system. This composite approach allows the system to benefit from both the cost reduction of lower sampling frequencies and the accuracy restoration through nonlinear compensation, achieving a balance between manufacturing ease and signal precision.
Data Source
AI summary
A signal modulation apparatus includes: a reference signal generator that generates an analog reference signal by removing at least one harmonic signal component corresponding to at least one higher-order frequency from a triangular wave signal; a modulation signal generator that performs pulse width modulation for comparing the analog reference signal with an analog input signal, thereby to generate an analog modulation signal; a digital signal converter that converts the analog modulation signal to a digital output signal; and a nonlinear converter that performs nonlinear conversion corresponding to waveform conversion for converting the triangular wave signal to the analog reference signal, on the digital output signal or the analog input signal.