Crystal Oscillator Electrode Layout for Frequency Accuracy
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Solution Overview
Problem
In existing crystal oscillators, the difference in parasitic capacitance between crystal electrodes and an output electrode leads to deteriorated frequency accuracy of the oscillation output signal.
Innovation Solution
The oscillator design includes a substrate with electrodes disposed in specific orientations and intervals to minimize the difference in parasitic capacitance between the first and second electrodes and the output electrode, using configurations such as varying electrode shapes and adding a shield electrode to reduce parasitic capacitance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the mounting electrodes corresponding to crystal terminals are increased in size to improve contact property, then the contact property is improved, but the difference in parasitic capacitance between crystal electrodes and output electrode increases, deteriorating frequency accuracy
Solution Approach 1:
The patent applies local quality by making the first electrode have a larger area than the second electrode. This asymmetric design compensates for the unequal parasitic capacitances by adjusting the local electrode properties, specifically making the first electrode larger to reduce its parasitic capacitance difference with the output electrode, thereby improving frequency accuracy while maintaining good contact properties
Solution Approach 2:
The patent changes the geometric parameters of the electrodes, specifically the area of the first and second electrodes. By making the first electrode larger than the second electrode, the parasitic capacitance of the first electrode increases, which compensates for the unequal spacing relationships and reduces the difference in parasitic capacitances, thus improving frequency accuracy
Data Source
AI summary
An oscillator includes: a resonator element; a circuit element electrically coupled to the resonator element and configured to output a clock signal; and a container accommodating the resonator element and the circuit element and including a substrate having a first surface on which the circuit element is mounted. The substrate includes a first electrode provided on the first surface and electrically coupled to the resonator element, a second electrode electrically coupled to the resonator element, and an output electrode configured to output the clock signal. The first electrode and the second electrode are disposed side by side in a first direction. The output electrode is disposed adjacent to the first electrode in a second direction orthogonal to the first direction. When a virtual line that passes through an end portion of the output electrode on the first electrode side and extends along the first direction is defined as a virtual line A, an interval between an end portion of the first electrode on the output electrode side and the virtual line A is larger than an interval between an end portion of the second electrode on the output electrode side and the virtual line A in the second direction.