Oscillator IC Layout Using Ground-Pad Shielding for Noise Accuracy
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Solution Overview
Problem
Existing integrated circuit apparatuses face issues with noise resistance due to radiation noise superimposed on DC voltage, leading to a deterioration in oscillator accuracy, and the increasing pad area ratio creates dead spaces that hinder size reduction and stable mounting.
Innovation Solution
The ground pad and DC voltage generation circuit are disposed to overlap in a plan view, with the ground pad functioning as a shielding member to suppress high-frequency noise and reduce potential fluctuations, allowing for efficient layout and accurate clock signal generation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the ground pad area is increased to improve noise shielding, then the noise resistance is improved, but the available area for other circuits is reduced
Solution Approach 1:
The patent merges the ground pad area with the DC voltage generation circuit by allowing the circuit to be disposed within or overlapping the ground pad region. This combines the noise shielding function of the ground pad with the voltage generation function, achieving both noise resistance improvement and efficient space utilization without requiring separate areas for each function.
Solution Approach 2:
The ground pad region is given multiple functions: it serves as both a noise shielding element and as the location for the DC voltage generation circuit. This multi-functionality allows the same physical space to provide both electromagnetic shielding and power supply functions, resolving the area conflict.
2Reliability
If the pad area ratio is increased to improve mounting stability, then the mounting reliability is improved, but the circuit size reduction is hindered
Solution Approach 1:
The patent combines the mounting function of the pad with the circuit integration function by allowing the DC voltage generation circuit to be disposed within the pad area. This merging enables the pad to serve dual purposes: providing mechanical mounting stability while simultaneously housing functional circuitry, thus achieving size reduction without compromising mounting reliability.
3Device complexity
If the DC voltage generation circuit is placed near the output buffer circuit, then the circuit complexity is reduced, but the noise resistance deteriorates due to radiation noise
Solution Approach 1:
The patent introduces the ground pad as an intermediary shielding element between the DC voltage generation circuit and the output buffer circuit. By disposing the DC voltage generation circuit within or overlapping the ground pad region, the ground pad acts as a mediator that provides electromagnetic shielding, allowing the circuits to be physically close while maintaining noise resistance.
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 configuration effectively reduces the transmission of high-frequency noise to the DC voltage generation circuit, maintaining oscillator accuracy and enabling a more compact integrated circuit apparatus by utilizing the ground pad region for the DC voltage generation circuit, thus preventing decreases in clock frequency accuracy.
Implementation Method 1
the ground pad and the DC voltage generation circuit are disposed so as to overlap with each other in a plan view... the ground pad functioning as a shielding member to suppress high-frequency noise
Data Source
AI summary
An integrated circuit apparatus includes an oscillation circuit that generates an oscillation signal by using a resonator, an output buffer circuit that outputs a clock signal based on the oscillation signal, a DC voltage generation circuit that generates a DC voltage used to generate the oscillation signal or the clock signal, a power source pad to which a power source voltage is supplied, a ground pad to which a ground voltage is supplied, and a clock pad via which the clock signal is outputted. The ground pad and the DC voltage generation circuit are disposed so as to overlap with each other in the plan view.