Split-Capacitor Oscillation Circuit for RF Interference Reduction

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Solution Overview

Problem

Conventional oscillation circuits in semiconductor integrated circuits face issues with high frequency wave currents causing interference and deteriorating the properties of other circuits, particularly at frequencies below 500 MHz, leading to increased size and cost when trying to mitigate these effects.

Innovation Solution

The oscillation circuit is designed with a resonance circuit that includes an inner capacitor and an outer inductor, along with an amplifier circuit, where the outer capacitor and inductor are positioned outside the semiconductor integrated circuit, and the wiring resistance is optimized to direct high frequency wave currents outside the circuit, minimizing interference with internal components.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Area of stationary object

If the inductor is disposed inside the semiconductor integrated circuit, then the area of the semiconductor integrated circuit is reduced, but the high frequency wave current causes interference with other circuits

Engineering Contradiction:

Improvearea of semiconductor integrated circuitVSAvoidinterference with other circuits

Core Design Contradiction:

Area of stationary objectVSObject-affected harmful factors

Solution Approach 1:

The capacitor is divided into two parts: an inner capacitor disposed inside the semiconductor integrated circuit and an outer capacitor disposed outside. This segmentation allows the high frequency wave current to flow through the outer capacitor outside the circuit, reducing interference with internal circuits while maintaining a compact integrated circuit design.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The outer capacitor is extracted from the semiconductor integrated circuit and disposed outside. This extraction directs the high frequency wave current path outside the circuit boundaries, eliminating the harmful interference effect on other internal circuits while the inner capacitor remains integrated for area efficiency.

Inventive Principle:

Principle #2Taking out (Extraction)

2Object-affected harmful factors

If the inductor is disposed outside the semiconductor integrated circuit, then interference with other circuits is reduced, but the area of the semiconductor integrated circuit increases

Engineering Contradiction:

Improveinterference with other circuitsVSAvoidarea of semiconductor integrated circuit

Core Design Contradiction:

Object-affected harmful factorsVSArea of stationary object

Solution Approach 1:

The capacitor is segmented into inner and outer portions, allowing the integrated circuit to maintain a compact area while the outer capacitor handles the high frequency current externally, reducing interference without requiring the entire circuit to be external.

Inventive Principle:

Principle #1Segmentation

3Object-affected harmful factors

If the oscillation amplitude is decreased to reduce interference, then interference with other circuits is reduced, but the purity of the oscillation signal is deteriorated

Engineering Contradiction:

Improveinterference with other circuitsVSAvoidpurity of oscillation signal

Core Design Contradiction:

Object-affected harmful factorsVSManufacturing precision

Solution Approach 1:

By segmenting the capacitor and creating separate current paths through inner and outer capacitors, the circuit maintains sufficient oscillation amplitude for signal purity while directing excess high frequency current externally to reduce interference effects on other circuits.

Inventive Principle:

Principle #1Segmentation

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 influence of high frequency wave currents on internal circuits, maintaining the integrity of reception sensitivity and other semiconductor integrated circuit properties while preventing property deterioration.

Implementation Method 1

a resonance circuit including an inner capacitor C1 to be disposed inside the semiconductor integrated circuit 60, and an outer capacitor C3 and an outer inductor L1 to be disposed outside the semiconductor integrated circuit 60

Methodology Applied

Scientific EffectElectromagnetic resonance: Resonance

Implementation Method 2

a conductive material constituting a current path of the conventional oscillation circuit radiates an electromagnetic wave

Methodology Applied

Scientific EffectElectromagnetic radiation: Electromagnetic Induction

Data Source

PatentUS8508305B2Oscillation circuit

Publication Date: 2013.08.13 LAPIS SEMICON CO LTD

AI summary

An oscillation circuit includes a resonance circuit and an amplifier circuit. The resonance circuit includes an inner capacitor to be disposed inside a semiconductor integrated circuit, and an outer capacitor and an outer inductor to be disposed outside the semiconductor integrated circuit. The amplifier circuit includes an input terminal and an output terminal both connected to the resonance circuit. Further, the resonance circuit includes a first closed circuit portion including the inner capacitor, the outer inductor, and a first wiring portion for connecting the inner capacitor and the outer inductor. The resonance circuit further includes a second closed circuit portion including the outer capacitor, the outer inductor, and a second wiring portion for connecting the outer capacitor and the outer inductor. The second closed circuit portion has a wiring resistance smaller than that of the first closed circuit portion.