Pseudo-Random Signal Spreading for Even-Harmonic Suppression
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Solution Overview
Problem
Existing methods for suppressing harmonic distortion in non-linear electronic circuits, such as the differential technique, are inefficient in canceling even-numbered harmonics and require duplicate signal paths, leading to increased costs and complexity.
Innovation Solution
A method involving the use of a pseudo random noise sequence to spread and despread signals before and after passing through a non-linear element, effectively separating even-numbered order terms from odd-numbered order terms by converting them into broadband noise, thereby reducing harmonic distortion without the need for duplicate signal paths.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If the differential technique is used to suppress even-numbered harmonic distortion, then the even-numbered harmonics are canceled out, but the circuit complexity and costs increase due to duplicate signal paths
Solution Approach 1:
The patent introduces a pseudo-random noise sequence as an intermediary signal that modulates the input signal before it passes through the non-linear element. This intermediary modulation allows the even-numbered harmonic distortion to be separated from the desired signal in the frequency domain, enabling selective suppression without requiring duplicate signal paths. The pseudo-random noise sequence acts as a mediator that transforms the distortion problem into a frequency-domain separation problem.
Solution Approach 2:
The patent changes the temporal parameters of the signal by modulating it with a pseudo-random noise sequence, which spreads the signal spectrum. This parameter change transforms the concentrated harmonic distortion at specific frequencies into a spread spectrum that can be selectively filtered. By changing the signal's spectral parameters through pseudo-random modulation, the patent achieves distortion suppression with a single signal path.
2Object-generated harmful factors
If the differential technique is used to suppress even-numbered harmonic distortion, then the even-numbered harmonics are canceled out, but the manufacturing costs increase due to additional components
Solution Approach 1:
The pseudo-random noise sequence serves as a cost-effective intermediary that enables distortion suppression through signal processing rather than hardware duplication. This approach replaces expensive duplicate passive components and amplifiers with a software-generated or hardware-efficient pseudo-random sequence generator and a simple modulator/demodulator pair, significantly reducing manufacturing costs.
Solution Approach 2:
The patent substitutes the mechanical/hardware-based differential technique with a signal-processing-based approach using pseudo-random modulation. Instead of physically duplicating the signal path with identical components, the invention uses mathematical transformation through pseudo-random sequencing to achieve the same distortion cancellation effect, replacing complex hardware with more economical signal processing operations.
3Object-generated harmful factors
If high-linearity components are used to reduce non-linearities, then the harmonic distortion is reduced, but the component costs and design complexity increase
Solution Approach 1:
The patent converts the harmful non-linear distortion into a useful separated signal component by modulating with pseudo-random noise. The non-linear elements still produce distortion, but the pseudo-random modulation causes the distortion products to fall into different spectral regions than the desired signal. This transforms the harmful distortion into a separable spectral component that can be easily filtered out, benefiting from the existing non-linearities rather than fighting them.
Solution Approach 2:
The patent changes the spectral parameters of both the desired signal and the distortion products through pseudo-random modulation. By spreading the signal spectrum and causing distortion products to appear at different spectral locations, the patent enables selective filtering without requiring high-linearity components. This parameter transformation approach simplifies the design requirements for the non-linear elements.
Data Source
AI summary
In a method for suppression of even-numbered harmonic distortion which occurs in a non-linear element 4, a signal x(n) is linked to a pseudo random noise sequence r(n), and is thus spread, before passing through the non-linear element 4. After passing through the non-linear element 4, the signal y*(n) is once again linked to the pseudo random noise sequence r(n). The signal y*(n) is thus despread while, in contrast, even-numbered order harmonic elements are once again spread, and remain as broadband noise.