Phase Detector Range Extension Without Cycle Slips
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Solution Overview
Problem
Phase detectors in phase locked loops have a limited linear phase detection range, leading to cycle slips and degraded acquisition time and modulation capability beyond this range.
Innovation Solution
The linear range of a conventional phase detector is extended by dividing it into smaller sub-ranges, where phase adjustments of 2π radians are made by ignoring or removing input pulse edges when the phase error exceeds a threshold, and compensating the output to maintain operation within the sub-range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the linear range of a conventional phase detector is extended beyond 2π radians, then the phase detection capability is improved, but cycle slips occur and degrade acquisition time and modulation capability
Solution Approach 1:
The phase detector's linear range is divided into smaller sub-ranges, with each sub-range handled by a dedicated phase detector unit. This segmentation allows the system to maintain linear operation within each sub-range while collectively covering a much wider total range, preventing cycle slips that would occur in a single extended-range detector.
Solution Approach 2:
A range detector acts as an intermediary component that determines which sub-range the current phase difference falls into. Based on this determination, it selects the appropriate phase detector unit to process the signal, enabling the system to operate reliably across extended ranges without cycle slips.
2Adaptability or versatility
If the linear range of a conventional phase detector is extended beyond 2π radians, then the phase detection capability is improved, but modulation capability is degraded
Solution Approach 1:
By segmenting the extended phase range into multiple sub-ranges and using dedicated phase detector units for each, the system maintains the modulation capability characteristics of conventional detectors within each sub-range while achieving extended overall coverage, thus avoiding the degradation that would occur in a single extended-range detector.
Solution Approach 2:
The range detector serves as an intermediary that ensures the phase detection process remains within optimal sub-ranges for modulation capability, selecting the appropriate detector unit based on the current phase difference to prevent capability degradation.
3Adaptability or versatility
If multiple phase detectors are used to cover extended ranges, then the linear operating range is improved, but device complexity increases
Solution Approach 1:
The phase detection function is segmented into multiple specialized units, each handling a specific sub-range. This segmentation, while increasing the number of components, organizes the complexity in a manageable way that enables extended range operation with maintained linearity.
Solution Approach 2:
The range detector acts as an intermediary that manages the complexity by automatically selecting the appropriate phase detector unit based on the input signal's phase difference, simplifying the control logic and making the extended-range system as easy to use as a single detector.
Data Source
AI summary
A method and apparatus for extending the linear range of a phase detector. In one embodiment, a limited range phase difference is generated between selected edges of first and second input signals, and an excursion of the limited range phase difference beyond a predetermined threshold is detected. In response to detecting the excursion of the limited range phase difference beyond a threshold, an edge of the first or second input signal is prevented from influencing subsequent generation of the limited range phase difference, and a compensated phase difference is generated, derived from the limited range phase difference and including a correction component which compensates for the effect of preventing said edge from influencing subsequent generation of the limited range phase difference.