Tdk Corporation

Paul B Kirby

Eiju Komuro

Roger William Whatmore

Qingxin Su

Masaaki Imura

A ladder-type film bulk acoustic resonator (FBAR) filter comprises two series FBARs and two parallel FBARs. Each FBAR has a top electrode, a bottom electrode, and a piezoelectric layer sandwiched between the top and bottom electrodes. The top electrodes of the two series FBARs form part of a signal line of a coplanar waveguide transmission line. The top electrodes of the two series FBARs are connected to associated circuitry. The two series FBARs have a common bottom electrode.

Film bulk acoustic resonator filter

Multiple thin film bulk acoustic resonators () configured in series () and parallel () within a coplanar waveguide line structure provides a compact ladder filter. The resonators () are formed over an opening () in a substrate () and connected to associated circuitry by one or more transmission lines formed on the substrate (). The arrangement of the resonators () between the ground and signal lines of a coplanar line structure provides a means of minimising the area of the filter. Embedding a ladder filter within the coplanar transmission line structure eliminates the need for wire bonds, thus simplifying fabrication. Embodiments for 2&#xd7;2, and hither order filters are described.

Film bulk acoustic resonator filters with a coplanar waveguide

An electric filter comprises a plurality of thin film bulk acoustic resonants () arranged in series and in parallel which have electrodes () of different working area (L) and optionally a piezoelectric layer () of different thickness (T).

Electric filter comprising a plurality of thin film bulk acoustic resonators

An electric filter comprises a plurality of thin film bulk acoustic resonators arranged in series and in parallel which have different thicknesses of one or more non-piezoelectric layers, for example top electrode.

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Northampton, United Kingdom

Paul B Kirby