Common-Ground Millimeter-Wave SPDT RF Switch With Shared Inductors

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Solution Overview

Problem

Existing RF SPDT switches face challenges in achieving both low loss and miniaturization, with issues of low reusability of components and switch arms, and difficulty in balancing performance and size.

Innovation Solution

A multi-inductor common-ground on-chip millimeter-wave SPDT RF switch design that efficiently reuses inductor components, utilizing coupled resonance working modes to achieve low loss and miniaturization by optimizing the switch arm structure and inductor connections.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If multiple SPST switches are paralleled to achieve broadband millimeter-wave communication, then bandwidth is improved, but insertion loss increases and switch size cannot be optimized

Engineering Contradiction:

ImprovebandwidthVSAvoidinsertion loss

Core Design Contradiction:

Adaptability or versatilityVSLoss of energy

Solution Approach 1:

The patent combines multiple SPST switch units into a unified SPDT switch structure with shared inductors and common grounding. This merging approach reduces the total number of independent components while maintaining broadband capability through the coupled resonance mechanism, thereby reducing insertion loss compared to simply paralleling multiple switches.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The shared inductors serve multiple functions: they provide impedance matching for both switch arms, create coupled resonance for broadband operation, and enable common grounding for improved isolation. This multi-functionality reduces component count and insertion loss while achieving the desired bandwidth.

Inventive Principle:

Principle #6Universality (Multi-functionality)

2Reliability

If multi-stage series-parallel transistor structure is used to achieve high isolation, then isolation is improved, but switch size becomes large and reusability is low

Engineering Contradiction:

ImproveisolationVSAvoidswitch size

Core Design Contradiction:

ReliabilityVSArea of stationary object

Solution Approach 1:

The patent merges the isolation function into the basic switch structure through common grounding and shared inductors. The coupled resonance mechanism naturally provides isolation between switch arms without requiring additional isolation stages, thereby achieving high isolation with a compact design.

Inventive Principle:

Principle #5Merging (Combining)

3Adaptability or versatility

If 1/4λ transmission lines are used for impedance matching, then bandwidth is improved, but switch size increases

Engineering Contradiction:

ImprovebandwidthVSAvoidswitch size

Core Design Contradiction:

Adaptability or versatilityVSArea of stationary object

Solution Approach 1:

The patent changes the impedance matching mechanism from wavelength-dependent 1/4λ transmission lines to frequency-independent coupled inductor resonance. This parameter change allows broadband operation without the size penalty of long transmission lines, as the coupled resonance can be achieved with compact on-chip inductors.

Inventive Principle:

Principle #35Parameter changes

4Power

If series-connected switch units are used to increase output power, then output power is improved, but insertion loss increases

Engineering Contradiction:

Improveoutput powerVSAvoidinsertion loss

Core Design Contradiction:

PowerVSLoss of energy

Solution Approach 1:

The patent combines multiple switch transistors into parallel configurations within each switch arm rather than series connections. This merging approach maintains high output power capability while reducing the cumulative insertion loss that would result from series-connected switch units.

Inventive Principle:

Principle #5Merging (Combining)

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 proposed switch achieves a wide bandwidth with an insertion loss of less than 1.5 dB and a return loss greater than 20 dB, effectively addressing the challenges of size and loss in existing RF switches.

Implementation Method 1

The other end of the first coupled inductor is connected to one end of the second coupled inductor... utilizing coupled resonance working modes to achieve low loss and miniaturization

Methodology Applied

Scientific EffectElectromagnetic coupling: Electromagnetic Induction

Implementation Method 2

utilizing coupled resonance working modes to achieve low loss and miniaturization by optimizing the switch arm structure and inductor connections

Methodology Applied

Scientific EffectResonance: Resonance

Data Source

PatentUS20250119120A1Multi-inductor common-ground on-chip millimeter-wave single-pole double-throw (SPDT) RF switch

Publication Date: 2025.04.10 NANJING UNIV OF POSTS & TELECOMM

AI summary

A multi-inductor common-ground on-chip millimeter wave single-pole double-throw radio frequency switch is provided. The radio frequency switch includes a first radio frequency port, a second radio frequency port, a third radio frequency port, a first switch arm and a second switch arm. Access points of output matching circuits in the two switch arms are respectively connected with a first compensation inductor and a second compensation inductor. The first compensation inductor, the second compensation inductor, and a first coupling inductor connected with the first radio frequency port are multiplexed to be grounded to a second coupling inductor.