Oscillator Error Detection for Harmonic Lock During Startup
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Solution Overview
Problem
Oscillators in electronic devices, such as processors, often start up with internal nodes in unknown states, leading to the output signal locking onto harmonic components instead of the intended frequency, resulting in frequency errors that can cause undesirable operation.
Innovation Solution
An error detection system using an open-loop chain of delay elements is employed to test the oscillator by comparing its output with a delayed representation of a start pulse, allowing for determination of whether the oscillator is operating at the correct frequency, and enabling adjustments or resets as necessary.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the oscillator starts up with internal nodes in unknown states, then the oscillator can begin operation quickly, but the output signal may lock onto harmonic components instead of the intended frequency
Solution Approach 1:
The patent applies preliminary action by performing frequency verification before the oscillator is fully operational. A test signal is applied to the oscillator during startup, and the actual frequency is measured and compared against the expected frequency before normal operation begins. This ensures that frequency errors are detected and corrected in advance, preventing harmonic locking during subsequent operation while maintaining quick startup once verification is complete.
2Measurement precision
If frequency verification is performed during oscillator operation, then frequency errors can be detected, but the detection system adds complexity to the oscillator design
Solution Approach 1:
The patent uses an intermediary approach by introducing a test signal generator and frequency measurement system that operates independently during startup verification. This separate verification subsystem applies a known test signal to the oscillator and measures the output frequency without interfering with the oscillator's normal operation once verified. The intermediary verification system allows accurate frequency detection while keeping the main oscillator design relatively simple, as the complex verification functions are isolated to a dedicated startup sequence.
Data Source
AI summary
An error detection system employs a chain of delay elements connected in an open loop configuration. To determine whether the oscillator is operating within a specified set of parameters, the error detection system applies a start pulse to an input of the open-loop chain of delay elements. The error detection system compares the resulting output signal with the output of the oscillator. If the oscillator has locked onto a harmonic of the intended output frequency, the comparison of the output signals will indicate an error.