Crystal Oscillator Ground Plane Filtering for RF Noise Jitter
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Solution Overview
Problem
Crystal oscillators in computing systems are sensitive to noise and external interference, leading to jitter in clock signals, particularly due to RF power injection from nearby devices.
Innovation Solution
A semiconductor device with a patterned reference plane acts as an inductor-capacitor (LC) resonant filter, selectively etched to attenuate RF noise from the clock signal without additional components, by forming patterns on the ground reference plane that interconnect and filter specific frequency bands.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional crystal oscillator circuitry is used without additional filtering components, then the device complexity is low and manufacturing is simple, but the oscillator is sensitive to RF noise causing jitter in clock signals
Solution Approach 1:
The patent combines the ground reference plane with the RF filtering function by etching patterns directly into the reference plane. This merging of the grounding function and filtering function eliminates the need for separate filtering components while maintaining clock signal stability against RF noise interference.
Solution Approach 2:
The reference plane serves multiple functions: it provides the standard grounding reference for the oscillator circuitry and simultaneously acts as an RF filter through the etched patterns. This multi-functionality reduces device complexity while improving reliability by filtering noise without adding extra components.
2Object-affected harmful factors
If additional shielding or filtering components are added to protect the crystal oscillator, then the noise filtering performance improves, but the device complexity and manufacturing difficulty increase
Solution Approach 1:
The filtering function is merged into the existing reference plane structure through selective etching, eliminating the need for separate filtering components. This approach maintains effective RF noise attenuation while simplifying the manufacturing process by using standard PCB fabrication techniques.
Solution Approach 2:
The patent changes the physical parameters of the reference plane by etching specific patterns with controlled geometry. By modifying the reference plane's structure through etching rather than adding components, the RF noise attenuation is achieved without increasing manufacturing complexity.
3Object-affected harmful factors
If the reference plane is patterned to filter RF noise, then the noise filtering capability is enhanced, but the manufacturing precision requirements increase
Solution Approach 1:
The patent achieves noise filtering by changing the reference plane's physical structure through etching patterns with specific dimensions. The filtering performance is controlled by adjusting etching parameters such as pattern size, spacing, and geometry, which can be optimized to balance filtering effectiveness with manufacturing precision capabilities.
4Device complexity
If conventional oscillator circuitry without integrated filtering is used, then the device complexity is low, but additional components are needed to achieve noise-free output
Solution Approach 1:
The patent merges the filtering function into the reference plane itself, eliminating the need for separate filtering components. This integration maintains low device complexity while ensuring noise-free clock signal output by providing inherent RF noise attenuation through the patterned reference plane.
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
The solution effectively filters out high-frequency noise from the clock signal, ensuring a noise-free output without the need for additional shielding or components, and can be easily integrated into existing semiconductor device designs.
Implementation Method 1
A semiconductor device with a patterned reference plane acts as an inductor-capacitor (LC) resonant filter, selectively etched to attenuate RF noise from the clock signal
Data Source
AI summary
An apparatus is provided which comprises: an oscillator circuit to generate a clock signal and transmit the clock signal over a signal line; a ground reference plane associated with the signal line; and one or more patterns formed in the ground reference plane, wherein the one or more patterns in the ground reference plane is to filter out noise from the clock signal transmitted over the signal line.