Pulse-Width Frequency Detection Circuit With Low-Pass Thresholding
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Solution Overview
Problem
Existing frequency detection circuits for periodic waves, such as clock signals, require complex configurations to accurately detect frequencies, which can hinder their operational simplicity and effectiveness in integrated circuit operations.
Innovation Solution
A frequency detection circuit comprising a pulse generator, low pass filters with varying cutoff frequencies, and a determination circuit that generates frequency detection signals based on filtered pulse signals, allowing for accurate frequency determination with a simple circuit configuration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a complex frequency detection circuit configuration is used, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The frequency detection circuit is segmented into three functional modules: a pulse generator that creates pulses with widths proportional to the periodic wave cycle, a low pass filter that selectively passes pulses based on frequency thresholds, and a determination circuit that generates detection signals. This segmentation allows each module to perform a specific function simply, achieving accurate frequency detection without overall circuit complexity
Solution Approach 2:
A low pass filter is introduced as an intermediary component between the pulse generator and determination circuit. The filter acts as a frequency threshold gate, allowing only pulses with widths corresponding to frequencies below a threshold to pass through. This intermediary simplifies the determination circuit's task and enables accurate frequency detection through a straightforward comparison mechanism
2Adaptability or versatility
If multiple low pass filters with different cutoff frequencies are used, then adaptability is improved, but device complexity increases
Solution Approach 1:
The circuit employs multiple low pass filters with different cutoff frequencies, each configured to detect specific frequency ranges. By having filters with varying thresholds (e.g., first cutoff frequency for high-frequency detection, second cutoff frequency for low-frequency detection), the circuit dynamically adapts to different input frequencies without requiring complex reconfiguration mechanisms
Solution Approach 2:
The determination circuit generates multiple frequency detection signals corresponding to different frequency ranges by utilizing outputs from multiple low pass filters. This partial action approach allows the circuit to cover a broad frequency spectrum by having each filter handle a specific portion of the frequency range, achieving comprehensive adaptability through distributed simple functions
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enables precise frequency detection of periodic waves with a straightforward circuit design, facilitating adaptable operation in integrated circuits by distinguishing between different frequency ranges.
Implementation Method 1
a low pass filter configured to selectively allow the pulse signal to pass therethrough
Implementation Method 2
each of the low pass filters includes one or more inverters that are serially coupled
Data Source
AI summary
A frequency detection circuit may include a pulse generator configured to generate a pulse signal having a pulse width proportional to a cycle of a periodic wave to be measured; a low pass filter configured to selectively allow the pulse signal to pass therethrough; and a determination circuit configured to generate a frequency detection signal based on the pulse signal having passed through the low pass filter.