Crystal Oscillator Start-Up Circuit Using Time-Variant Stimulus
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Solution Overview
Problem
Crystal oscillators experience prolonged start-up times due to slow regeneration processes, which are exacerbated by low power conditions in battery-operated devices, necessitating a reduction in start-up time while maintaining power efficiency.
Innovation Solution
A time-variant, periodic or aperiodic stimulus is introduced to the crystal oscillator during start-up, either as voltage or current, to actively insert energy and speed up the oscillation process, differing from prior art methods that rely on noise amplification and positive feedback.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the crystal oscillator operates under low power conditions to maintain power efficiency, then power consumption is reduced, but start-up time increases due to the amplifier's inability to introduce sufficient energy to the crystal quickly
Solution Approach 1:
The patent applies preliminary action by introducing a start-up stimulus signal before normal operation begins. This stimulus signal pre-charges the crystal and amplifier circuit, enabling the oscillator to reach its operating state faster when power is applied, thereby reducing start-up time without increasing steady-state power consumption.
Solution Approach 2:
The patent implements dynamics by making the amplifier's power consumption time-variant. During the start-up phase, the amplifier operates at higher power to quickly build oscillation, then transitions to lower power for steady-state operation. This dynamic power adjustment resolves the contradiction between low power operation and fast start-up.
2Loss of time
If the amplifier introduces more energy to the crystal during start-up to reduce start-up time, then start-up time decreases, but power consumption increases
Solution Approach 1:
The patent applies periodic action through the use of a start-up stimulus signal that is applied only during the initial start-up period and then discontinued. This periodic, time-limited energy input provides the necessary boost to reduce start-up time while not contributing to steady-state power consumption, as the stimulus is pulsed rather than continuous.
Solution Approach 2:
The patent implements parameter changes by varying the amplifier's operating parameters (power consumption, gain) as a function of time. During start-up, parameters are set to values that enable fast oscillation build-up; after start-up, parameters are adjusted to lower values for power-efficient steady-state operation. This time-dependent parameter adjustment resolves the energy-time trade-off.
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
This approach significantly reduces start-up time without increasing power consumption during normal operation, as the stimulus is stopped after a pre-established period, allowing the oscillator to transition swiftly to routine oscillations.
Implementation Method 1
A widespread type of low power frequency source is the crystal oscillator. It consists of a piezoelectric crystal and an inverting amplifier, connected to each other to form a negative feedback loop.
Implementation Method 2
The relation between these mechanical and electrical vibrations is bidirectional, that is, mechanical vibrations result in voltage vibrations and vice versa.
Data Source
AI summary
A method and apparatus for speeding up the start-up process of a crystal oscillator. The energy required for starting oscillations is inserted to the crystal by a stimulus in the form of a time-variant voltage or current pattern, either periodic or aperiodic. The stimulus is stopped after a pre-established period, then the oscillator continues to operate in its normal mode and completes the start-up process significantly faster, compared to a start-up process not comprising the above stimulus.