Oscillation Circuit Dual-Loop Abnormality Detection

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Solution Overview

Problem

Existing oscillation circuits in integrated circuits face challenges in detecting abnormalities, particularly when the sub oscillation circuit stops, leading to potential system failures, and existing solutions either fail to detect issues or increase the overall size of the circuit.

Innovation Solution

An oscillation circuit with a main oscillation circuit and a sub oscillation circuit, equipped with first and second abnormality detection sections, which utilize frequency-divided clocks and cycle counting to detect abnormalities, allowing for detection even when the sub oscillation circuit has stopped, while maintaining a compact size.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a new oscillation circuit is provided to check the sub oscillation circuit, then abnormality detection capability is improved, but the overall size of the oscillation circuit increases

Engineering Contradiction:

Improveabnormality detection capabilityVSAvoidoverall size of oscillation circuit

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The sub oscillation circuit is designed to perform dual functions: it serves as both the timing reference for the main oscillation circuit and as the monitoring mechanism for detecting abnormalities in the main oscillation circuit. By making the sub oscillation circuit multi-functional, the patent eliminates the need for a separate monitoring circuit, thereby maintaining compact size while improving abnormality detection capability.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The sub oscillation circuit monitors its own operation status and the operation status of the main oscillation circuit. When the main oscillation circuit stops or becomes abnormal, the sub oscillation circuit detects this through its own oscillation characteristics and generates corresponding detection signals. This self-monitoring mechanism eliminates the need for external monitoring circuits.

Inventive Principle:

Principle #25Self-service

2Reliability

If a watchdog timer with self-reset function is installed, then abnormality detection is improved, but the system becomes vulnerable when the clock stops

Engineering Contradiction:

Improveabnormality detectionVSAvoidsystem vulnerability when clock stops

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The sub oscillation circuit acts as an intermediary between the main oscillation circuit and the abnormality detection function. It receives the clock signal from the main oscillation circuit and processes it through its own oscillation mechanism. When the main oscillation circuit stops, the sub oscillation circuit continues to operate and detects the abnormality through changes in its own oscillation characteristics, thereby mediating the failure detection without being affected by the clock stop.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Reliability

If existing abnormality detection technology is used, then detection capability is improved, but detection fails when the sub oscillation circuit stops

Engineering Contradiction:

Improveabnormality detection capabilityVSAvoiddetection capability when sub oscillation circuit stops

Core Design Contradiction:

ReliabilityVSAdaptability or versatility

Solution Approach 1:

Instead of having the sub oscillation circuit be monitored by a separate circuit, the patent inverts the approach by having the sub oscillation circuit itself perform the monitoring function. The sub oscillation circuit uses its own oscillation state and the frequency-divided clock to detect abnormalities in the main oscillation circuit, including cases where the main oscillation circuit has stopped. This inverted monitoring approach ensures detection capability remains functional even when the sub oscillation circuit stops.

Inventive Principle:

Principle #13The other way round (Inversion)

Data Source

PatentUS9453881B2Oscillation circuit, integrated circuit, and abnormality detection method

Publication Date: 2016.09.27 LAPIS SEMICON CO LTD

AI summary

There is provided an oscillation circuit including: a main oscillation circuit that outputs a specific main clock to an internal circuit; a sub oscillation circuit that outputs a sub clock having a different frequency to the frequency of the main oscillation circuit; a first abnormality detection section that detects an abnormality according to a number of main clock cycles output from the main oscillation circuit within a predetermined period corresponding to sub clock outputs from the sub oscillation circuit; and a second abnormality detection section that detects an abnormality according to a frequency divided clock of the main clock output from the main oscillation circuit that has been frequency-divided and the sub clock output from the sub oscillation circuit.