Frequency Measurement Circuit With Dynamic Counting Selection
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Solution Overview
Problem
Existing frequency measurement methods, such as direct counting and reciprocal counting, have limited measurable ranges and require complex circuits and increased costs due to the need to switch between different clock signals based on the input signal frequency.
Innovation Solution
A frequency measurement apparatus that includes a measurement period setting circuit, first and second counter circuits, first and second frequency calculation circuits, and a frequency selection circuit, which calculates and selects between two frequencies (f1 and f2) using a reference clock signal, allowing for a wider measurement range without the need for multiple clock signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a direct counting method is used to measure high frequency input signals, then measurement accuracy is improved, but the method becomes unsuitable for low frequency signals with large measurement errors
Solution Approach 1:
The patent implements dynamic switching between direct counting and reciprocal counting methods based on the measured frequency range. The system automatically selects the appropriate measurement method according to the input signal frequency, enabling accurate measurement across a wide frequency spectrum while maintaining high precision for both high and low frequency signals
Solution Approach 2:
The patent changes the measurement parameter from fixed method selection to dynamic method switching. By monitoring the frequency range and adjusting the measurement method accordingly, the system achieves both high measurement accuracy and wide frequency adaptability, resolving the contradiction between precision and versatility
2Measurement precision
If a reciprocal counting method is used to measure low frequency input signals, then measurement accuracy is improved, but the method becomes unsuitable for high frequency signals with large measurement errors
Solution Approach 1:
The system dynamically adapts the measurement method based on the input signal characteristics. For low frequency signals, reciprocal counting is automatically selected to achieve high accuracy, while for high frequency signals, direct counting is used, thus maintaining both precision and wide frequency range coverage
Solution Approach 2:
The measurement approach parameter is changed from static to dynamic based on frequency detection. This allows the system to optimize measurement accuracy for each frequency range while maintaining versatility across the entire measurable spectrum
3Adaptability or versatility
If multiple clock signals are used to widen frequency measurement range, then adaptability is improved, but circuit complexity and cost increase
Solution Approach 1:
The patent makes a single reference clock signal perform multiple functions by using it in both direct counting and reciprocal counting modes. This eliminates the need for multiple dedicated clock signals, reducing circuit complexity and cost while maintaining wide frequency measurement capability
Solution Approach 2:
The system merges the functionality of multiple clock signal paths into a single unified reference clock signal that serves both measurement methods. This consolidation reduces the number of required clock sources and associated circuitry, achieving cost-effective wide-range frequency measurement
4Measurement precision
If measurement period is lengthened to reduce measurement error for low frequency signals, then measurement accuracy is improved, but measurement time increases
Solution Approach 1:
The system dynamically adjusts the measurement period based on the input signal frequency. For low frequency signals, a longer measurement period is automatically selected to reduce measurement error, while for high frequency signals, a shorter period suffices. This dynamic adjustment maintains high accuracy across all frequencies without unnecessarily increasing measurement time
Solution Approach 2:
The measurement period parameter is changed from fixed to variable based on frequency detection. This allows optimization of the measurement period for each frequency range, achieving high measurement accuracy while minimizing measurement time through adaptive parameter selection
Data Source
AI summary
A frequency measurement apparatus includes: a measurement period setting circuit that sets a measurement period based on a reference clock signal; a first counter circuit that counts the number of pulses of the reference clock signal in a period based on an input signal during the measurement period; a second counter circuit that counts the number of pulses of the input signal during the measurement period; a first frequency calculation circuit that calculates a first frequency; a second frequency calculation circuit that calculates a second frequency; and a frequency selection circuit that selects the first frequency or the second frequency as a frequency of the input signal.