Stacked BAW Resonator-IPD Filter for Low-Loss 6 GHz+ Operation

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Current Bulk Acoustic Wave (BAW) filters face challenges in filtering signals above 6 GHz due to increasing losses at high frequencies, limiting their performance and complexity in wireless devices.

Innovation Solution

A BAW assist filter structure is developed by stacking a BAW resonator onto an integrated passive device (IPD) with a transducer having electrodes and a piezoelectric layer, which is electrically coupled to the IPD, reducing insertion loss and enabling high-frequency filtering with improved performance and design flexibility.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Speed

If BAW filters are used for high-frequency signals above 6 GHz, then filtering capability is improved, but losses increase significantly

Engineering Contradiction:

Improvefrequency of operationVSAvoidinsertion loss

Core Design Contradiction:

SpeedVSLoss of energy

Solution Approach 1:

The filter is divided into two functional segments: a BAW resonator segment for high-frequency signal processing and an IPD segment for electrical circuit functions. This segmentation allows each component to operate in its optimal frequency range, with the BAW resonator handling high-frequency signals above 6 GHz while the IPD handles lower-frequency electrical operations, thereby reducing overall system losses at high frequencies

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The IPD serves as an intermediary component between the BAW resonator and the external circuitry. By placing the IPD in close electrical proximity to the BAW resonator, the patent minimizes parasitic inductance and resistance in the interconnect paths, thereby reducing insertion loss while enabling high-frequency operation above 6 GHz

Inventive Principle:

Principle #24Intermediary (Mediator)

2Volume of moving object

If BAW resonator size is decreased for higher frequencies, then miniaturization is achieved, but electrical length parasitic loss increases

Engineering Contradiction:

ImproveBAW resonator sizeVSAvoidelectrical length parasitic loss

Core Design Contradiction:

Volume of moving objectVSLoss of energy

Solution Approach 1:

The patent merges the BAW resonator and IPD into a single stacked package where the BAW resonator is positioned directly over the IPD. This merging eliminates the need for separate mounting and long interconnect paths, thereby reducing electrical length parasitic losses while maintaining the miniaturized form factor required for high-frequency operation

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The patent transitions from a planar layout to a three-dimensional stacked configuration. By stacking the BAW resonator vertically over the IPD rather than placing them side-by-side in the same plane, the patent reduces the electrical path length between components while maintaining a compact footprint, thereby reducing parasitic losses without sacrificing miniaturization

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

3Reliability

If filter complexity is increased for better performance, then filtering capability is improved, but device size increases

Engineering Contradiction:

Improvefilter performanceVSAvoiddevice size

Core Design Contradiction:

ReliabilityVSVolume of moving object

Solution Approach 1:

The IPD is designed to perform multiple functions: it provides electrical circuit elements (inductors, capacitors, resistors), serves as a mounting platform for the BAW resonator, and enables close electrical coupling to reduce parasitic losses. This multi-functionality allows complex filter performance to be achieved without proportionally increasing device size, as the same IPD structure supports multiple functionalities

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 BAW assist filter structure achieves low insertion loss and mitigates electrical length parasitic loss, allowing for effective filtering of high frequencies above 6 GHz with enhanced filter performance and flexibility in filter design.

Implementation Method 1

a transducer with electrodes and a piezoelectric layer between the electrodes

Methodology Applied

Scientific EffectPiezoelectric effect: Piezoelectric Effect

Implementation Method 2

Bulk Acoustic Wave (BAW) resonators are used in many high-frequency communication applications

Methodology Applied

Scientific EffectAcoustic resonance: Resonance

Data Source

PatentUS11923827B2Bulk acoustic wave resonator stacked onto an integrated passive device

Publication Date: 2024.03.05 QORVO US INC

AI summary

Disclosed is a Bulk Acoustic Wave (BAW) assist filter structure with a BAW resonator stacked onto an integrated passive device (IPD). In exemplary aspects disclosed herein, the BAW filter structure includes a transducer with electrodes and a piezoelectric layer between the electrodes. The IPD is electrically coupled to the BAW resonator and provides a high frequency of operation. In such a configuration, the BAW assist filter structure has a low insertion loss and mitigates electrical length parasitic loss due to the close electrically proximity of the BAW resonator stacked onto the IPD. Further, the BAW assist filter structure is able to filter high frequencies and provides improved filter performance and greater flexibility in design of a filter transfer function.