Digital Chirp Signal Generator With Precise Frequency Switching
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Solution Overview
Problem
Current methods for generating chirp signals, such as phase-locked loops and analog frequency synthesis, face challenges in precision control and high costs, making it difficult to produce chirp signals with high accuracy and low costs.
Innovation Solution
A signal generator employing a control circuit to generate variable control word information and a base time unit, using a Time-Average-Frequency Direct Period Synthesis (TAF-DPS) technique to produce a target signal with variable frequency, allowing for precise control and low-cost generation of chirp signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If phase-locked loop is used to generate chirp signal, then signal generation is achieved, but output frequency modulation mode cannot be precisely controlled resulting in deterioration of chirp signal performance
Solution Approach 1:
The patent replaces the traditional phase-locked loop (analog control system) with a digital frequency synthesis system using direct digital frequency synthesis (DDFS) technique. The DDFS uses digital counters and phase accumulators to generate frequency-modulated signals, providing precise digital control over frequency modulation parameters without the inherent limitations of analog PLL systems. This substitution enables accurate control of frequency deviation and modulation rate while maintaining signal quality.
Solution Approach 2:
The patent implements precise control of frequency modulation parameters by using digital phase accumulators with configurable bit widths and wrap-around points. By changing the phase accumulator increment value and wrap-around threshold, the system can precisely control the frequency deviation (Δf) and modulation rate (fm) parameters. This digital parameter control mechanism allows for accurate generation of chirp signals with specified frequency characteristics.
2Ease of manufacture
If analog frequency synthesis method is used to generate chirp signal, then frequency synthesis is achieved, but mixer and filter are required resulting in very high cost and impossibility to be implemented on a chip
Solution Approach 1:
The patent replaces analog mixing and filtering operations with digital signal processing techniques. Instead of using physical mixers to combine signals and filters to select frequency components, the system uses digital phase accumulation and binary-coded frequency selection. This digital approach eliminates the need for complex analog RF components, enabling full integration on a single chip while reducing component count and manufacturing cost.
Solution Approach 2:
The patent uses digital representation of frequency information through binary-coded control words that specify desired output frequencies. Instead of physically generating each frequency through analog synthesis, the system stores frequency information in digital form and uses digital counters to generate the corresponding signals. This copying approach allows for flexible frequency selection without requiring physical analog components for each frequency point.
3Reliability
If traditional methods are used to generate chirp signal, then signal generation is achieved, but cost is very high
Solution Approach 1:
The patent replaces expensive analog frequency synthesis equipment with a digital signal generation system implemented in integrated circuit form. The digital frequency synthesizer uses standard digital logic components (counters, multiplexers, adders) that can be manufactured using standard CMOS fabrication processes. This substitution dramatically reduces component cost while maintaining signal generation capability, making the system suitable for cost-sensitive applications.
Solution Approach 2:
The patent designs a universal frequency synthesis architecture that can generate multiple frequency signals and modulation waveforms (sine, square, triangular) using a single integrated circuit. The system uses programmable phase accumulators and lookup tables that can be configured through digital control words to produce different frequency outputs and waveform types. This multi-functionality eliminates the need for separate dedicated circuits for each signal type, reducing overall system cost while maintaining reliable chirp signal generation.
Data Source
AI summary
The present application provides a signal generator, comprising a control circuit configured to receive input information, and generate variable control word information based on the received input information; a base time unit generation circuit configured to generate a base time unit; and a signal generation circuit configured to receive the variable control word information from the control circuit and receive the base time unit from the base time unit generation circuit, and generate a target signal having a variable frequency based on the received variable control word information and the received base time unit.