Clock Frequency Detection Circuit Using Charge-Discharge Sampling
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Solution Overview
Problem
Existing frequency-detection circuits require complex designs to accurately detect specific frequencies of clock signals, which is inefficient for scenarios where only changes in frequency need to be detected.
Innovation Solution
A frequency-detecting circuit comprising a control-signal generating circuit, a charging and discharging path, and a control-voltage generating circuit, which generates a first control signal and a second control signal delayed relative to the first. The charging and discharging path performs charging and discharging processes under the control of the second signal, and the control-voltage generating circuit samples the voltage at the output terminal before discharging to output a corresponding voltage signal related to the frequency of the clock signal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a complex circuit is designed to accurately detect specific frequency values, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent extracts only the essential information needed (frequency magnitude comparison) rather than measuring the complete frequency value. By using a charging-discharging mechanism that only needs to compare charging time against a reference, the circuit achieves frequency detection capability without complex frequency measurement components, thereby reducing device complexity while maintaining sufficient measurement precision for the application.
Solution Approach 2:
The patent transforms the frequency detection problem into a time measurement problem. Instead of directly measuring frequency parameters, the circuit converts frequency information into charging time duration, which can be compared against a reference time period. This parameter transformation simplifies the detection mechanism from complex frequency analysis to simple time comparison, resolving the contradiction between precision and complexity.
2Device complexity
If a simple circuit is used to detect only frequency changes, then device complexity is reduced, but measurement precision deteriorates
Solution Approach 1:
The patent introduces an intermediary charging capacitor and timing mechanism that mediates between the simple circuit structure and the frequency detection requirement. The charging-discharging process acts as an intermediary transformation that converts frequency information into measurable time intervals, allowing a simple circuit to achieve precise frequency change detection through this intermediate time-based representation.
3Measurement precision
If accurate frequency value detection is implemented, then measurement precision is improved, but loss of time increases due to complex processing
Solution Approach 1:
The patent replaces complex frequency measurement mechanisms with a simpler time-based charging-discharging system. Instead of using elaborate frequency counting or spectral analysis methods that consume significant processing time, the circuit uses direct time-domain measurement of capacitor charging duration, which can be quickly compared against a reference period. This substitution dramatically reduces detection time while maintaining the ability to accurately determine frequency magnitude.
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
This solution allows for efficient detection of frequency changes in clock signals without requiring accurate detection of specific frequencies, enabling direct determination of frequency magnitude through voltage value detection and facilitating its use as an input for subsequent circuits.
Implementation Method 1
a charging and discharging path, coupled to the control-signal generating circuit, and performing a charging process or a discharging process under control of the second control signal
Data Source
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AI summary
A frequency-detecting circuit (100), a DCC, and an electronic device. The frequency-detecting circuit (100) includes a control-signal generating circuit (110) generating a first control signal (CKp) and a second control signal (CKPD) delayed relative to the first control signal (CKp); a charging and discharging path (120), under control of the second control signal (CKPD), during a period with a pulse width when the second control signal (CKPD) is at a high level, performing the discharging process, and performing the charging process during another period when the second control signal (CKPD) is at a low level; and a control-voltage generating circuit (130), sampling values of a voltage of an output terminal of the charging and discharging path (120) before the discharging process during a period with a pulse width when the first control signal (CKp) is at the high level, to output a corresponding first voltage signal (Vi).