Rf Micro Devices, Inc.

Aleh Loseu

Jayanti Jaganatha Rao

Kevin J Gamble

The present disclosure relates to a two-track surface acoustic wave (SAW) device that has a first SAW track and a second SAW track. The second SAW track may include an interconnecting grating that divides an acoustic cavity of the second SAW track into two acoustic cavities, which are acoustically coupled to one another. The first SAW track and the second SAW track may be electrically coupled to one another transversally via a first re-radiation interconnection and a second re-radiation interconnection. When the two-track SAW device is used in a bandpass filter, by including the interconnecting grating, insertion loss and roll-off response characteristics of the bandpass filter may be improved. Further, in one embodiment of the two-track SAW device, addition of capacitance between the re-radiation connections may improve return loss of the two-track SAW device.

Two-track surface acoustic wave device with interconnecting grating

Embodiments of the disclosure relate to a process of making a surface acoustic wave device having a series connected interdigitated transducers with center chirping. A piezoelectric substrate is provided. Two acoustic reflectors may be formed on the piezoelectric substrate to define an acoustic cavity between the acoustic reflectors. In addition, at least three beta interdigitated transducers (IDTs) adjacent one another are formed on the piezoelectric substrate in electrical series with each other and aligned in acoustic series with each other between the acoustic reflectors, such that the at least three beta IDTs comprise at least one inner beta IDT between two outer beta IDTs, a center portion of the at least one inner beta IDT being chirped.

Process of making series connected interdigitated transducers with center chirping

The present invention relates to dual-mode SAW devices (DMSDs), which may allow for clean layouts of SAW device elements and provide low impedance with reduced insertion loss, and may increase broadband rejection by improving parasitic characteristics. In one embodiment of the present invention, a parallel set of DMSDs is cascaded with another parallel set of DMSDs. Internal connections between the four DMSDs may be electrically floating, which may further improve parasitic characteristics. With electrically floating internal connections, the parallel set of DMSDs may share a common grating structure, thereby reducing the size and complexity of a DMSD, which may further improve parasitic characteristics. The DMSDs may be used in radio frequency (RF) applications, such as SAW filters.

Architectures using multiple dual-mode surface acoustic wave devices

The present disclosure relates to a two-track surface acoustic wave (SAW) device that has a reduced size compared to a traditional two-track SAW device by eliminating an internal ground connection node of the traditional two-track SAW device. The internal ground connection node is eliminated by coupling an internal ground interconnection to an external ground connection node through an interconnecting ground grating, which is part of one of two SAW tracks of the two-track SAW device. The internal ground interconnection is located in an internal region of the two-track SAW device that is defined by the two SAW tracks and by two electrical interconnections between the two SAW tracks.

Two-track surface acoustic wave structure without internal pads

The present invention provides an interleaved IDT that is connected to and overlaps adjacent IDTs. In particular, the interleaved IDT may be connected to both an input IDT and an output IDT via corresponding bus bars. The first bus bar of the interleaved IDT is connected to the bus bar of the input IDT, and the other bus bar of the interleaved IDT is connected to a bus bar of the output IDT. The interleaved IDT is coupled electrically to the respective input and output ports of the overall surface acoustic wave architecture. As such, the bus bars of the respective input and output IDTs are effectively extended, such that the adjacent edges of the respective input and output IDTs partially overlap one another in an interdigitated fashion at the interleaved IDT.

Interleaved interdigitated transducers

An acoustic cavity of a surface acoustic wave (SAW) architecture is defined on a piezoelectric substrate by two acoustic reflectors are formed on a piezoelectric substrate. The surface acoustic wave architecture may include at least one alpha interdigitated transducer (IDT) at least three beta IDTs which are placed in acoustic series within the acoustic cavity. The alpha IDT is electrically coupled to a first interface. The beta IDTs are coupled in electrical and acoustic series and are associated with a second interface. At least three beta IDTs are adjacent one another. An additional reflector or an alpha IDT may be placed between two of the beta IDTs.

SAW architecture with series connected interdigitated transducers

The present invention provides a surface acoustic wave (SAW) architecture wherein two acoustic reflectors are formed on a piezoelectric substrate to define an acoustic cavity between the acoustic reflectors. At least one alpha interdigitated transducer (IDT) may be provided, and at least three beta IDTs are provided. These IDTs are placed in acoustic series within the acoustic cavity. The alpha IDT is electrically coupled to a first interface. The beta IDTs are coupled in electrical and acoustic series and are associated with a second interface. In certain embodiments, the at least three beta IDTs are adjacent one another, while in other embodiments an additional reflector or an alpha IDT may be placed between two beta IDTs. Edge chirping may be employed in adjacent edge portions of adjacent beta IDTs. Traditional edge chirping may be provided in adjacent edge portions of adjacent alpha and beta IDTs.

Edge chirping within series connected interdigitated transducers

The present invention provides a surface acoustic wave (SAW) architecture wherein two acoustic reflectors are formed on a piezoelectric substrate to define an acoustic cavity between the acoustic reflectors. At least one alpha interdigitated transducer (IDT) may be provided, and at least three beta IDTs are provided. These IDTs are placed in acoustic series within the acoustic cavity. The alpha IDT is electrically coupled to a first interface. The beta IDTs are coupled in electrical and acoustic series and are associated with a second interface. In certain embodiments, the at least three beta IDTs are adjacent one another, while in other embodiments an additional reflector or an alpha IDT may be placed between two beta IDTs.

Saw architecture with series connected interdigitated transducers

A SAW architecture is provided with two acoustic reflectors formed on a piezoelectric substrate defining an acoustic cavity between the acoustic reflectors. At least one alpha IDT may be provided, and at least three beta IDTs are provided. These IDTs are placed in acoustic series within the acoustic cavity. The alpha IDT is electrically coupled to a first interface. The beta IDTs are coupled in electrical and acoustic series and associated with a second interface. In certain embodiments, the at least three beta IDTs are adjacent one another, while in other embodiments an additional reflector or an alpha IDT may be placed between two beta IDTs. The beta IDTs include two outer beta IDTs and an inner beta IDT located between the two outer beta IDTs. The inner beta IDT may be chirped in a center portion, wherein the area outside of the center portion is not chirped.

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Greensboro, NC, United States of America

Aleh Loseu