Clock Distribution Chip Readiness Signaling for Settled Output Clocks
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Solution Overview
Problem
Existing clock distribution systems face challenges in determining when output clock signals are ready, leading to potential system errors or reduced performance due to unknown settling times for frequency and phase configurations, which is particularly problematic in systems with strict timing constraints like data converter and processor blocks supporting JESD204B signaling.
Innovation Solution
A system ready signal is provided by a clock distribution chip that includes a phase-locked loop, divider and phase control circuit, and a controller, which monitors the state of finite state machines to indicate when output clock signals have reached desired frequencies and phases, ensuring all signals are ready for distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a PLL and divider circuit are used to generate multiple frequency-divided clock signals, then the system can provide stable low-jitter clock signals at different frequencies, but it becomes difficult to determine when all output clock signals are ready, leading to unknown settling times
Solution Approach 1:
The patent implements a system ready circuit that continuously monitors the state of finite state machines controlling the divider circuits and generates a system ready signal. This feedback mechanism allows the system to automatically determine when all clock signals have settled to their target frequencies and phases, eliminating the need for fixed waiting periods and enabling precise timing control in downstream circuits.
Solution Approach 2:
The patent uses finite state machines to pre-establish control sequences for the divider circuits. These state machines transition through predefined states that systematically configure each divider circuit before the system is considered ready. This preliminary structured action ensures all clocks are properly configured before downstream circuits attempt to use them, preventing timing errors.
2Adaptability or versatility
If multiple divider circuits are used to provide different frequency divisions, then the system can support multiple clock frequencies, but the complexity of monitoring and determining readiness of all signals increases
Solution Approach 1:
The patent implements a universal system ready circuit that can monitor any number of divider circuits through a standardized interface. The finite state machines provide a unified control mechanism that works regardless of how many divider circuits are present or what frequency divisions are required. This multi-functional approach allows the same monitoring infrastructure to handle variable configurations without increasing complexity proportionally.
Solution Approach 2:
The system ready circuit acts as an intermediary between the multiple divider circuits and the downstream application logic. Instead of requiring complex monitoring in each downstream circuit or direct monitoring of all dividers, the system ready circuit consolidates the readiness determination and provides a single standardized signal to external users, simplifying the overall system architecture.
3Measurement precision
If the system waits for all clock signals to be ready before operation, then timing accuracy is improved, but system startup time and productivity are reduced
Solution Approach 1:
The system ready signal provides real-time feedback on clock signal readiness, allowing downstream circuits to immediately begin operation as soon as clocks are ready rather than waiting for a predetermined time. This feedback-driven approach eliminates unnecessary waiting periods while ensuring timing accuracy is maintained, optimizing both precision and startup performance.
Solution Approach 2:
The patent implements dynamic readiness determination where the system adapts to the actual settling time of the clock signals rather than using fixed timing. The finite state machines and system ready circuit continuously assess the actual state of clock signals, allowing the system to transition to operational mode as soon as readiness conditions are met, whether that takes minimal or extended time based on the specific configuration.
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
The system ready signal efficiently notifies external users of clock signal readiness, preventing errors and optimizing system performance by ensuring all output clocks are configured correctly before use, even in applications with strict timing requirements.
Implementation Method 1
One or more phase locked loops (PLLs) are typically used to recover a noisy reference clock signal, also referred to as a reference signal, and to create stable, low jitter signals. PLLs can be used in, for example, frequency synthesizers, telecommunications systems, chip-to-chip communication systems, the like, or any combination thereof.
Implementation Method 2
Clock generation circuits can provide multiple low jitter clock signals derived from a selection of noisy reference clocks in an integrated circuit.
Implementation Method 3
a high precision tunable voltage controlled oscillator can be phase-locked to a noisy reference clock signal, and the PLL can operate to suppress phase noise and to attenuate jitter
Implementation Method 4
The divider and phase control circuit is configured to receive a reference clock signal and to provide output clock signals. The output clock signals are each frequency divided relative to the reference clock signal.
Data Source
AI summary
Provided herein are apparatus and methods for system ready in a clock distribution chip or system. In certain configurations, a communication system includes a clock generation circuit having a divider and phase control circuit to provide output clock signals. The communication system further includes a system ready circuit to provide a system ready signal indicative of whether all of the output clock signals are ready.