Cross-Domain Clock Monitoring for Oscillator Frequency Errors
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Solution Overview
Problem
Synchronous digital circuits with multiple clock domains face challenges in maintaining correct timing and reliability, particularly in safety-critical applications like automotive systems, due to potential frequency errors in oscillators that can lead to circuit failure and non-compliance with safety standards.
Innovation Solution
Implementing clock monitors with synchronization mechanisms and comparison circuitry to detect frequency errors by synchronizing clock signals from different oscillators and producing error indications when count values exceed predetermined thresholds, ensuring correct clock operation across various transition scenarios.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multiple oscillators operate at different frequencies in different clock domains, then circuit functionality and performance are improved, but frequency errors and timing reliability deteriorate
Solution Approach 1:
The patent implements feedback by continuously monitoring the frequency of each oscillator against its nominal value and generating error indications when deviations occur. The clock monitor circuits provide real-time feedback about oscillator performance, enabling the system to detect and respond to frequency errors that could compromise timing reliability across multiple clock domains.
Solution Approach 2:
The patent introduces intermediary clock monitor circuits that act as mediators between the oscillators and the rest of the digital circuitry. These monitors synchronize clock signals from different oscillators and compare them against reference values, serving as an intermediate layer that ensures timing reliability without interfering with the functional independence of multiple clock domains.
2Speed
If clock frequency is increased for high-speed signal processing, then processing speed is improved, but power consumption increases
Solution Approach 1:
The patent segments the digital circuit into multiple independent clock domains, each operating at different frequencies optimized for their specific functions. High-speed signal processing portions operate at higher frequencies while low-frequency control functions operate at lower frequencies, allowing the system to achieve high processing speed where needed without unnecessarily consuming power across the entire circuit.
Solution Approach 2:
The patent applies local quality by assigning different clock frequencies to different portions of the circuit based on their specific functional requirements. Critical high-speed paths receive higher frequency clocks for maximum performance, while non-critical portions operate at lower frequencies to minimize power consumption, creating a locally optimized frequency distribution across the circuit.
3Ease of manufacture
If clock frequency assumptions are made for circuit layout, then design simplicity is improved, but circuit reliability deteriorates when assumptions are not met
Solution Approach 1:
The patent performs preliminary action by establishing clock monitor circuits during the design phase that proactively detect frequency deviations before they cause circuit failure. The monitors are configured with predetermined frequency ranges and thresholds, allowing the system to identify potential reliability issues early and take corrective action before assumptions about clock frequency are violated.
Solution Approach 2:
The patent implements beforehand cushioning by creating a protective monitoring layer that cushions the circuit against frequency variations. The clock monitors act as a buffer that detects and signals frequency errors before they can propagate through the circuit and cause unreliable operation, providing a safety margin that protects the overall system reliability.
Data Source
AI summary
Clock monitors for circuits having a plurality of oscillators. The clock monitors produce an error indication when one oscillator is determined to be outside of a desired operating range or beyond a defined threshold with respect to a second oscillator. The clock monitors include a synchronizer configured to receive a clock signal from a first oscillator of the plurality of oscillators and synchronize the received clock signal with a second oscillator and to produce a synchronized clock signal. The clock monitors can include a counter configured to produce a count value based on synchronized clock signal. The clock monitors include comparison circuitry configured to receive the count value and produce an error indication when the count value is outside a predetermined range. The clock monitors may be used to ensure correct clock operation for different transition scenarios, e.g., turning on or off a certain clock or power domain.