DDS Sine Wave Generation for Real-Time Distortion Analysis
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Solution Overview
Problem
Existing methods for generating sinusoidal waves in direct digital synthesis are limited by the finite number of points, which restricts frequency synthesis and often require trigonometric look-up tables, making them inefficient for real-time generation and distortion analysis.
Innovation Solution
A method and apparatus using a direct digital synthesizer (DDS) to generate sinusoidal waveforms by producing a stream of phase numbers, canceling harmonics, and combining analog outputs to create a composite signal for real-time distortion analysis and correction, enabling efficient transmission to a circuit-under-test.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a finite length array is used to generate sine waves by cycling through pre-calculated values, then the implementation is simple and memory-based, but the frequency synthesis is limited and cannot achieve continuous frequency resolution
Solution Approach 1:
The patent replaces the mechanical/memory-based approach of cycling through finite arrays with a mathematical algorithm (CORDIC) that computes sine wave values on-the-fly using iterative coordinate rotation, enabling continuous frequency synthesis without lookup tables
Solution Approach 2:
The system transitions from static pre-calculated arrays to dynamic real-time computation where phase values are continuously updated and sine wave values are generated adaptively based on the current phase state, allowing flexible frequency control
2Ease of operation
If trigonometric look-up tables are used for wave generation, then the generation process is straightforward, but the system complexity increases and real-time generation efficiency decreases
Solution Approach 1:
The patent substitutes trigonometric look-up tables with the CORDIC algorithm, which uses only basic arithmetic operations (addition, subtraction, bit shifting) to compute sine and cosine values, thereby reducing memory requirements and access complexity while maintaining real-time generation capability
Solution Approach 2:
The CORDIC algorithm is self-contained and iterative, computing each sine wave value based on the previous state without requiring external lookup tables, making the system self-sufficient and reducing overall device complexity
3Measurement precision
If discrete Fourier transform methods are used, then the analysis is performed on fixed points, but continuous frequency analysis and real-time generation are not achieved
Solution Approach 1:
The patent implements continuous frequency analysis by using the CORDIC algorithm to generate sine wave values at every clock cycle without discrete sampling intervals, enabling both high frequency resolution and real-time generation capability simultaneously
Solution Approach 2:
The system pre-computes phase values using the phase accumulator before they are needed for sine wave generation, and the CORDIC algorithm is pre-configured with the necessary iteration counts to achieve the desired precision, enabling real-time operation
Data Source
AI summary
A system, method, and apparatus for distortion analysis is provided. A method in accordance with at least one embodiment of the present disclosure may include receiving a clock frequency at a direct digital synthesizer (DDS) and generating at least one stream of phase numbers via said DDS. The method may further include generating a digital sine wave using, at least in part, said clock frequency and said at least one stream of phase numbers. Of course, additional implementations are also within the scope of the present disclosure.