Fundamental Frequency Detection Using Feedback Loop Peak Locking
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Solution Overview
Problem
Existing frequency detectors, such as zero-crossing detectors, require high power consumption and significant silicon area due to the need for high sampling rates and signal pre-conditioning to accurately detect signal frequencies, especially in noisy environments.
Innovation Solution
A frequency detector implemented as a feedback control loop with a phase error detector, loop controller, and digitally controlled oscillator, which reduces power consumption and silicon area by locking onto the fundamental frequency of an input signal and filtering out noise, allowing for efficient operation at lower sampling rates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If zero-crossing detection methods are used to accurately detect signal frequencies, then measurement precision is improved, but use of energy increases due to high sampling rate requirements
Solution Approach 1:
The patent changes the detection parameter from zero-crossing points to peak detection. By detecting the peak of the sinusoidal signal and using the time difference between consecutive peaks, the system achieves accurate frequency measurement without requiring high sampling rates. This parameter change allows operation at lower sampling rates (e.g., 1/4 to 1/10 of the signal frequency) while maintaining measurement accuracy.
2Measurement precision
If zero-crossing detectors operate at high sampling rates to count each zero-level crossing, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent changes the detection parameter from zero-crossing points to peak detection. By detecting the peak of the sinusoidal signal and using the time difference between consecutive peaks, the system achieves accurate frequency measurement without requiring high sampling rates. This parameter change allows operation at lower sampling rates (e.g., 1/4 to 1/10 of the signal frequency) while maintaining measurement accuracy.
3Measurement precision
If signal pre-conditioning is implemented to remove noise before zero-crossing detection, then measurement precision is improved, but device complexity increases due to additional devices
Solution Approach 1:
The patent extracts only the essential feature of the signal (the peak) rather than attempting to process or filter the entire signal waveform. By focusing detection on the peak amplitude point and ignoring other portions of the waveform including noisy regions, the system achieves noise immunity without requiring additional filtering devices or pre-conditioning circuitry.
Solution Approach 2:
The patent introduces an intermediary comparison mechanism where the current signal amplitude is compared against a stored peak value. This intermediary comparison process identifies peak points without requiring complex signal processing, effectively filtering out noise through the comparison operation rather than through dedicated filtering hardware.
4Ease of operation
If zero-crossing detectors count all zero-level amplitudes including spurious ones, then ease of operation is improved, but measurement precision deteriorates in noisy conditions
Solution Approach 1:
The patent changes the detection parameter from zero-crossing points to peak detection. By detecting the peak of the sinusoidal signal and using the time difference between consecutive peaks, the system achieves accurate frequency measurement without requiring high sampling rates. This parameter change allows operation at lower sampling rates (e.g., 1/4 to 1/10 of the signal frequency) while maintaining measurement accuracy.
Data Source
AI summary
A system and method to detect the fundamental frequency of an electric input signal using a feedback control loop including a phase error detector, a loop controller, and a digitally controlled oscillator. The frequency detector may detect the fundamental frequency of an electric input signal and produce an output signal representing the fundamental frequency of the electric input signal. The frequency detector may further include a filter that may be coupled to the frequency detector output signal in order to remove spurious tones or noise from the output signal.