Crystal Oscillator Pulse Injection for Low-Power Stable Oscillation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing crystal oscillators consume significant power due to continuous driving of the amplifier, necessitating improvements in pulse injection methods to reduce complexity and power consumption.
Innovation Solution
A current source charges a capacitor, which periodically injects charge into the crystal through switches timed to occur at the peaks and troughs of the crystal's sine wave, with a comparator circuit adjusting the current based on output magnitude to control power consumption and output amplitude.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the amplifier is continually driven to maintain oscillation, then the oscillation stability is improved, but the power consumption increases significantly
Solution Approach 1:
The patent applies periodic pulse injection into the crystal oscillator circuit instead of continuous amplifier driving. A capacitor is charged during each oscillation cycle and then discharged through a switch to inject a periodic charge pulse into the crystal, maintaining oscillation with significantly reduced power consumption compared to continuous driving.
Solution Approach 2:
The patent uses feedback mechanisms to detect the oscillator output magnitude and adjust the pulse injection timing and amplitude accordingly. This ensures stable oscillation is maintained while optimizing power consumption by adapting the injection parameters to the actual oscillation state.
2Use of energy by moving object
If pulse injection is used to reduce power consumption, then the power efficiency is improved, but the device complexity increases
Solution Approach 1:
The patent combines multiple functions into integrated circuit blocks to reduce overall complexity. The timing circuit that generates pulse injection signals is integrated with the oscillator circuit, and the gain control circuit that adjusts amplifier gain based on output magnitude is merged with the existing amplifier stage, reducing the number of discrete components needed.
Solution Approach 2:
The patent designs the switch and capacitor network to serve multiple purposes: they provide pulse injection for power savings, while also functioning as part of the timing mechanism and output coupling network. This multi-functionality reduces the need for separate dedicated components for each function.
3Power
If the amplifier gain is increased to maintain output magnitude, then the output signal strength is improved, but the power consumption increases
Solution Approach 1:
The patent implements dynamic gain control where the amplifier gain is adjusted in real-time based on the detected output magnitude. The gain control circuit modifies the amplifier operating point dynamically to maintain constant output amplitude while minimizing power consumption, rather than using fixed high gain.
Solution Approach 2:
The patent changes the operating parameters of the amplifier dynamically by adjusting its gain based on feedback from the output magnitude detection. This allows the amplifier to operate at optimal power consumption levels while maintaining the required output signal strength through adaptive parameter modification.
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 reduces power consumption while maintaining stable oscillation by accurately timing pulse injections and adjusting current to match output requirements, achieving low power operation.
Implementation Method 1
Cs represents the motional capacitance. It represents the piezoelectric charge gained from a displacement in the crystal.
Implementation Method 2
A capacitor is coupled to be charged by the current source and periodically injects a charge from the capacitor into the crystal
Data Source
AI summary
A crystal oscillator includes a current source that charges a capacitor. A charge on the capacitor is periodically injected into a crystal of the crystal oscillator. A switch couples the capacitor to the crystal and a timing circuit controls the switch to cause the charge to be injected beginning at approximately a peak of a crystal output signal. The timing circuit is configurable into a self-resonant mode for calibration of a delay through the timing circuit by coupling an output of the timing circuit to an input of the timing circuit. A comparator compares a magnitude of the crystal output signal to a reference voltage and supplies compare results to a gain control circuit. The gain control circuit adjusts the current from the current source to adjust the charge being injected into the crystal from the capacitor to thereby control the magnitude of the crystal output signal.