Crystal Oscillator Start-Up Circuit for Low-Voltage Stability
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Solution Overview
Problem
Conventional crystal resonators with low transconductance and low current consumption face challenges in starting oscillation under high temperature and low supply voltage conditions, leading to instability and potential device crashes.
Innovation Solution
An oscillating signal generating device comprising a crystal oscillator, a resistor, and an oscillating start-up circuit, with a control circuit that enables and disables the start-up circuit to reduce power consumption and maintain oscillation, using a control signal to change the inverter mode and output the oscillating signal generated by the crystal resonator.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the crystal resonator is designed with low transconductance and low current consumption, then power consumption is reduced and standby time is prolonged, but the ability to start oscillating under high temperature and low supply voltage conditions deteriorates
Solution Approach 1:
The oscillating start-up circuit is activated before the main oscillating circuit to preliminarily establish oscillation conditions. The start-up circuit generates an initial oscillating signal that helps the main crystal resonator circuit start oscillating reliably under high temperature and low voltage conditions, without requiring continuous operation of the start-up circuit during normal operation.
2Use of energy by moving object
If the crystal resonator is designed with low transconductance and low current consumption, then power consumption is reduced, but the stability of the crystal resonator deteriorates
Solution Approach 1:
The oscillating start-up circuit acts as an intermediary that provides the necessary drive strength to the crystal resonator without requiring the main oscillating circuit to have high current consumption. The start-up circuit temporarily supplies additional current to ensure stable oscillation establishment, after which the main circuit operates at low current consumption while maintaining stability through the already-established oscillation.
3Reliability
If the oscillating start-up circuit is continuously enabled, then reliable oscillation is maintained, but power consumption increases
Solution Approach 1:
The oscillating start-up circuit operates periodically rather than continuously. It is enabled during startup and when oscillation stability is needed, then disabled during normal stable operation. The control circuit monitors oscillation status and activates the start-up circuit only when necessary, achieving reliable oscillation while minimizing power consumption through periodic rather than continuous operation.
Data Source
AI summary
An oscillating signal generating device includes an oscillating circuit and a control circuit. The oscillating circuit includes: a resonator having a first terminal and a second terminal for generating an oscillating signal, a resistive element having a first terminal coupled to the first terminal of the resonator, and a second terminal coupled to the second terminal of the resonator, and an oscillating start-up circuit having an input terminal coupled to the first terminal of the resonator and an output terminal coupled to the second terminal of the resonator. The control circuit generates a control signal to change the oscillating start-up circuit into a disable mode from an enable mode when the oscillating circuit generates an oscillating output signal under an operation mode, and outputs the oscillating signal generated by the resonator as the oscillating output signal of the oscillating circuit.