Abstract: A method for fabricating a resonator, and in particular, a thin film bulk acoustic resonator (FBAR), and a resonator embodying the method are disclosed. An FBAR is fabricated on a substrate by reducing mass from a top electrode layer. For a substrate having multiple resonators, mass is reduced from only selected resonator to provide resonators having different resonance frequencies on the same substrate.

Abstract: A method for fabricating a resonator, and in particular, a thin film bulk acoustic resonator (FBAR), and a resonator embodying the method are disclosed. A resonator is fabricated on a substrate, and its top electrode 56 is oxidized to form a oxide layer 58. For a substrate having multiple resonators, the top electrode 56 of only selected resonator is oxidized to provide resonators having different resonance frequencies on the same substrate.

Abstract: A bulk acoustic resonator having a high quality factor is formed on a substrate having a depression formed in a top surface of the substrate. The resonator includes a first electrode, a piezoelectric material and a second electrode. The first electrode is disposed on the top surface of the substrate and extends beyond the edges of the depression by a first distance to define a first region therebetween. The piezoelectric material is disposed on the top surface of the substrate and over the first electrode, and the second electrode is disposed on the piezoelectric material. The second electrode includes a portion that is located above the depression. The portion of the second electrode that is located over the depression has at least one edge that is offset from a corresponding edge of the depression by a second distance to define a second region therebetween. The first and second regions have different impedances, as a result of the different materials located in the two regions.

Abstract: A bulk acoustic resonator having a high quality factor is formed on a substrate having a depression formed in a top surface of the substrate. The resonator includes a first electrode, a piezoelectric material and a second electrode. The first electrode is disposed on the top surface of the substrate and extends beyond the edges of the depression by a first distance to define a first region therebetween. The piezoelectric material is disposed on the top surface of the substrate and over the first electrode, and the second electrode is disposed on the piezoelectric material. The second electrode includes a portion that is located above the depression. The portion of the second electrode that is located over the depression has at least one edge that is offset from a corresponding edge of the depression by a second distance to define a second region therebetween. The first and second regions have different impedances, as a result of the different materials located in the two regions.

Abstract: An FBAR-based duplexer that comprises a first port, a second port, a third port, a first band-pass filter connected between the first port and the third port and a series circuit connected between the second port and the third port. The first band-pass filter includes a first ladder circuit having shunt and series elements. Each of the elements of the first ladder circuit comprises a film bulk acoustic resonator (FBAR). The series circuit includes a 90° phase shifter in series with a second band-pass filter. The second band-pass filter includes a second ladder circuit having shunt and series elements. Each of the elements of the second ladder circuit comprises a film bulk acoustic resonator. A band-pass filter comprising shunt elements and series elements in which the series elements and the shunt elements are connected to form a ladder circuit, and each of the elements includes a film bulk acoustic resonator (FBAR).

Abstract: The invention includes an edge-triggered comparator circuit comprising a first Josephson junction connected between a signal input node and an output node and a sampler network coupled to the output node. The first Josephson junction is part of a low inductance SQUID which exhibits a periodic transfer function whose periodicity is a function of the current injected into the SQUID. The sampler network includes a second Josephson junction connected between a sampling terminal and the output node and a third Josephson junction connected between the output node and a point of reference potential. "N" comparator circuits embodying the invention may be interconnected to form an "N"-bit flash analog-to-digital (A/D) converter. The A/D converter may include an R-2R resistive ladder network connected between an analog signal input terminal and a point of reference potential. The resistive ladder network has N nodes with a different comparator being connected to each node.