Non-Reciprocal SAW Filter Using Single-Signal Parametric Modulation

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Solution Overview

Problem

Conventional non-reciprocal filters require multiple clock signals with precise phase relationships, leading to increased size and cost, and maintenance challenges due to the need for local oscillators, which complicates achieving low insertion loss and high isolation in wireless communication systems.

Innovation Solution

A non-reciprocal filter design utilizing a single modulation signal with asymmetrical transmission lines and a parametric amplifier, eliminating the need for multiple clock signals and local oscillators, and incorporating a surface acoustic wave structure with tunable frequency characteristics.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional non-reciprocal filters use multiple clock signals with precise phase relationships, then isolation capability is improved, but device complexity and size increase

Engineering Contradiction:

Improveisolation capabilityVSAvoiddevice complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent combines multiple clock signals into a single modulation signal that modulates a resonator. This resonator then generates the necessary phase-related signals internally, eliminating the need for separate clock signal sources and their associated local oscillators, thereby reducing device complexity while maintaining isolation capability

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The single modulation signal serves multiple functions: it modulates the resonator to generate phase-related signals, controls the non-reciprocal behavior, and eliminates the need for multiple dedicated clock sources. This multi-functionality reduces the overall number of components required in the system

Inventive Principle:

Principle #6Universality (Multi-functionality)

2Reliability

If conventional non-reciprocal filters use multiple local oscillators, then isolation capability is improved, but manufacturing cost increases

Engineering Contradiction:

Improveisolation capabilityVSAvoidmanufacturing cost

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The patent merges multiple local oscillator functions into a single resonator that is modulated by one modulation signal. This resonator internally generates all necessary phase-related signals, eliminating the need for multiple expensive local oscillator components and their associated circuitry, thereby reducing manufacturing cost while preserving isolation performance

Inventive Principle:

Principle #5Merging (Combining)

3Reliability

If conventional non-reciprocal filters use multiple clock signals with precise phase relationships, then isolation capability is improved, but maintenance difficulty increases

Engineering Contradiction:

Improveisolation capabilityVSAvoidmaintenance difficulty

Core Design Contradiction:

ReliabilityVSEase of repair

Solution Approach 1:

The patent combines multiple clock signal sources into a single resonator-based signal generation system. This eliminates the need to synchronize multiple independent oscillators and reduces the number of components that can drift or fail, significantly simplifying maintenance while maintaining the precise phase relationships necessary for isolation capability

Inventive Principle:

Principle #5Merging (Combining)

4Reliability

If conventional non-reciprocal filters use multiple clock signals, then isolation capability is improved, but insertion loss increases

Engineering Contradiction:

Improveisolation capabilityVSAvoidinsertion loss

Core Design Contradiction:

ReliabilityVSLoss of energy

Solution Approach 1:

The patent combines multiple signal paths into a single resonator-based generation system, reducing the number of signal conversion and switching operations that cause loss. The resonator efficiently generates the required signals with better energy efficiency, reducing insertion loss while maintaining isolation capability

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 solution achieves low insertion loss and high isolation with reduced size and complexity, enabling efficient signal processing in wireless communication systems and supporting full-duplex operations without magnetic components.

Implementation Method 1

incorporating a surface acoustic wave structure with tunable frequency characteristics

Methodology Applied

Scientific EffectSurface acoustic wave: Surface Acoustic Wave

Implementation Method 2

utilizing a single modulation signal with asymmetrical transmission lines and a parametric amplifier

Methodology Applied

Scientific EffectParametric amplification:

Data Source

PatentUS11973490B2Non-reciprocal filter

Publication Date: 2024.04.30 THE TRUSTEES OF COLUMBIA UNIV IN THE CITY OF NEW YORK

AI summary

A non-reciprocal filter with parametric amplification to obtain non-reciprocal propagation of forward and reverse signals is disclosed. The non-reciprocal filter may include two asymmetrical transmission lines and a current source. The filter, when implemented in the acoustics domain using surface acoustic waves (SAW), may operate in a phase-coherent or a phase-incoherent degenerate mode, providing low insertion loss and high decibels of isolation.