Tunable Active Silicon Coupler Linearity

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Solution Overview

Problem

Electromagnetic couplers, such as RF couplers, face challenges with substrate-induced nonlinearity, leading to harmonic generation and reduced performance due to capacitive and inductive effects from the handle wafer substrate.

Innovation Solution

The use of a silicon on insulator (SOI) wafer with an active semiconductor layer and a voltage terminal to reduce substrate effects by applying a supply voltage, which increases the conductivity of the active layer, acting as a ground plane to shield the coupler from the handle wafer, thereby improving linearity and reducing second harmonic generation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a conventional RF coupler uses a handle wafer substrate, then the coupler structure is simple and easy to manufacture, but substrate-induced nonlinearity occurs leading to harmonic generation and reduced performance

Engineering Contradiction:

Improvecoupler performanceVSAvoidsubstrate-induced nonlinearity

Core Design Contradiction:

ReliabilityVSObject-generated harmful factors

Solution Approach 1:

An active semiconductor layer is introduced as an intermediary between the handle wafer substrate and the transmission lines. This layer acts as a mediator that blocks the harmful capacitive and inductive effects from the substrate while allowing the transmission lines to function normally. The active layer with applied voltage creates a conductive barrier that prevents substrate-induced nonlinearity from affecting the RF signal path.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The conductivity of the active semiconductor layer is dynamically changed by applying different voltages to it. By adjusting the voltage parameter, the layer's electrical properties are modified to optimize its shielding effect against substrate effects. This parameter change allows the same structure to adapt to different operating conditions and minimize harmonic generation.

Inventive Principle:

Principle #35Parameter changes

2Reliability

If an active semiconductor layer with voltage terminal is added to reduce substrate effects, then linearity and performance are improved, but device complexity increases

Engineering Contradiction:

ImprovelinearityVSAvoidcoupler structure

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The active semiconductor layer is merged with the existing coupler structure, combining the substrate shielding function with the transmission line support function. Rather than adding a completely separate shielding component, the active layer is integrated into the substrate stack, serving dual purposes: structural support and electrical shielding against substrate effects.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The active semiconductor layer performs multiple functions simultaneously: it provides mechanical support as part of the substrate structure, acts as an electrical shield against substrate-induced nonlinearity, and can be dynamically tuned via voltage application. This multi-functionality reduces the need for additional separate components, thereby limiting the increase in overall device complexity.

Inventive Principle:

Principle #6Universality (Multi-functionality)

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 application of a supply voltage to the active semiconductor layer in the electromagnetic coupler assembly effectively decreases substrate-induced nonlinearity, enhancing the coupler's performance by reducing second harmonic generation and improving linearity.

Implementation Method 1

applying a supply voltage, which increases the conductivity of the active layer, acting as a ground plane to shield the coupler from the handle wafer

Methodology Applied

Scientific EffectElectrical Conductivity: Conduction (electrical)

Implementation Method 2

The coupled transmission line is one of inductively coupled to the main transmission line and capacitively coupled to the main transmission line

Methodology Applied

Scientific EffectInductive coupling: Electromagnetic Induction

Implementation Method 3

The coupled transmission line is one of inductively coupled to the main transmission line and capacitively coupled to the main transmission line

Methodology Applied

Scientific EffectCapacitive coupling: Capacitance

Data Source

PatentUS9953938B2Tunable active silicon for coupler linearity improvement and reconfiguration

Publication Date: 2018.04.24 SKYWORKS SOLUTIONS INC

AI summary

An electromagnetic coupler assembly includes a handle wafer having an oxide layer disposed on a first surface thereof. A layer of active semiconductor is disposed on the oxide layer and includes a voltage terminal to receive a supply voltage. A layer of dielectric material is disposed on the layer of active semiconductor. A main transmission line is disposed on the layer of dielectric material. A coupled transmission line is disposed on the layer of active semiconductor and is one of inductively coupled to the main transmission line and capacitively coupled to the main transmission line. At least a portion of one of the main transmission line and the coupled transmission line is disposed directly above at least a portion of the layer of active semiconductor.