Flip-Flop Phase Detector for Wider Range and Jitter Tolerance
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Solution Overview
Problem
Conventional phase detectors, such as those using Hogge phase detectors, face limitations in operation range and jitter tolerance due to the difficulty in producing narrow pulse widths on the order of tens of picoseconds, affecting the phase detection accuracy and synchronization in communication systems.
Innovation Solution
A phase detector with a flip-flop and a detection unit that selects either the input signal or its inverted signal based on a control signal to detect phase differences between designated edges of the input signal and a periodic signal, utilizing NAND and NOR gates to enhance edge detection precision and jitter tolerance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If an XOR gate is used in a Hogge phase detector to detect phase difference, then the phase detection function is achieved, but the pulse width cannot be narrowed to tens of picoseconds, limiting operation range and jitter tolerance
Solution Approach 1:
The invention divides the phase detection function into two separate detection paths: one detecting the rising edge of the data signal and another detecting the falling edge. Each path uses dedicated flip-flops and logic gates to generate pulse signals independently. This segmentation allows each path to be optimized for narrow pulse width while maintaining accurate phase detection capability.
Solution Approach 2:
The invention dynamically selects which edge (rising or falling) to detect based on the phase relationship between clock and data signals. By switching between detecting rising edges or falling edges, the system adapts to different operating conditions and maintains optimal pulse width and detection accuracy across varying signal conditions.
2Adaptability or versatility
If conventional phase detection methods are used, then basic phase detection is achieved, but the operation range is limited due to inability to produce narrow pulse widths
Solution Approach 1:
The invention performs preliminary edge detection using dedicated flip-flops that are pre-configured to capture either rising or falling edges. By preparing these detection paths in advance and using dedicated logic gates for each edge type, the system can rapidly respond to phase changes and generate narrow pulses across a wider operation range.
Solution Approach 2:
The invention changes the detection parameter from a single edge type to multiple edge types (rising and falling edges). By monitoring both edge types and selecting the appropriate one based on signal characteristics, the system expands its operational range while maintaining precise pulse width control through dedicated logic paths.
3Reliability
If a single edge detection method is used, then the circuit is simple, but jitter tolerance is low due to limited operation range
Solution Approach 1:
The invention merges multiple edge detection paths into a unified phase detection system. Both rising edge detection and falling edge detection paths are combined, with their outputs fed into a selection mechanism. This merging approach increases jitter tolerance by providing multiple detection opportunities while keeping the overall circuit manageable through shared components like the charge pump and loop filter.
Solution Approach 2:
The invention implements feedback by monitoring the outputs of both rising edge and falling edge detection paths and using this information to control the charge pump. The feedback mechanism selects which detection path provides valid phase error information, allowing the system to maintain high jitter tolerance by adaptively using the most reliable detection path under current signal conditions.
Data Source
AI summary
The operation range of a phase detector provided with a flip-flop is improved, and the jitter tolerance of a receiving circuit is enhanced. The phase detector includes a holding unit and a detection unit. In the phase detector, the holding unit holds an input signal in synchronization with a predetermined periodic signal. The detection unit detects a phase difference between a designated edge and the predetermined periodic signal on the basis of a signal held in the holding unit. The designated edge is designated by a control signal that designates one of a rising edge and a falling edge of the input signal as the designated edge.