Oscillation circuit, oscillator, electronic device, mobile object, and oscillator manufacturing method
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Solution Overview
Problem
Voltage-controlled temperature-compensated crystal oscillators (VC-TCXO) with a minimal number of terminals face challenges in maintaining frequency accuracy due to the variation in load capacity during temperature compensation adjustments, as the control terminal is used for both frequency control and temperature compensation, leading to potential deterioration in frequency accuracy.
Innovation Solution
The oscillation circuit incorporates a selection unit that controls the voltage applied to a variable capacity element, allowing for separate voltage settings during normal operation and temperature compensation modes, ensuring the capacity value remains consistent and reducing frequency accuracy deterioration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the control terminal is used for both frequency control and temperature compensation, then the number of terminals is reduced, but frequency accuracy deteriorates due to load capacity variation during adjustment
Solution Approach 1:
The patent segments the voltage control function by introducing a switching element that separates the control terminal's roles: during normal operation, the control terminal connects to the variable capacity element for frequency control; during temperature compensation adjustment, it disconnects and connects to a voltage generation element. This segmentation allows independent optimization of each function, maintaining frequency accuracy while preserving terminal minimization.
Solution Approach 2:
The patent implements dynamic switching of the control terminal's connection state based on operational mode. A switching element dynamically connects or disconnects the control terminal from the variable capacity element and connects it to a voltage generation element during adjustment. This dynamic reconfiguration ensures the variable capacity element maintains consistent load capacity regardless of the control terminal's input state, thereby maintaining frequency accuracy.
2Ease of operation
If the control terminal is disconnected from the AFC circuit during temperature compensation adjustment, then temperature compensation can be adjusted independently, but the variable capacity element operates at incorrect capacity value causing frequency accuracy deterioration
Solution Approach 1:
The patent introduces a voltage generation element as an intermediary that provides a predetermined voltage to the variable capacity element during temperature compensation adjustment. This intermediary ensures the variable capacity element operates at the correct capacity value even when disconnected from the AFC circuit, preventing frequency accuracy deterioration while allowing independent adjustment.
Solution Approach 2:
The patent prepares a voltage generation element in advance that can provide the appropriate predetermined voltage to the variable capacity element before adjustment begins. This preliminary preparation ensures that when the control terminal is disconnected from the AFC circuit for adjustment, the variable capacity element already has the correct voltage applied, maintaining proper operating conditions throughout the adjustment process.
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 maintains precise frequency control and reduces frequency accuracy deterioration by allowing independent voltage control during temperature compensation, ensuring stable oscillation characteristics.
Implementation Method 1
a variable capacity element (36, 37)
Implementation Method 2
a resonator (piezoelectric resonator) such as a crystal resonator
Data Source
AI summary
An oscillation circuit includes a circuit for frequency adjustment, a variable capacity control circuit in which a voltage to be output therefrom is controlled with either a voltage which is input from a terminal T1 or a voltage other than the voltage which is input from the terminal T1, a circuit for oscillation which is provided with a varactor and to which a signal from the circuit for frequency adjustment and a signal from the variable capacity control circuit are input, and a three-terminal switch which outputs the voltage which is input from the terminal T1 to either the circuit for frequency adjustment or the variable capacity control circuit.