Resonant filter using mm wave cavity

Inventors

Gudeman, Christopher S. • Tamijani, Abbas Abbaspour

Assignees

Atomica Corp

Abstract

Systems and methods for forming a mm wave resonant filter include a lithographically fabricated high Q resonant structure. The resonant structure may include a plurality of cavities, each cavity having a characteristic frequency that defines its passband. A filter may include a plurality of resonant structures, and each resonant structure may include a plurality of cavities. These cavities and filters may be fabricated lithographically.

Core Innovation

The invention provides a mm wave passband filter for a mm-wave emission source, fabricated photolithographically on a substrate. The filter comprises at least one resonant cavity formed in a plurality of substrates by registration of voids formed using photolithographic methods in adjacent ones of the plurality of substrates to form a substrate stack. The resonant cavity in the substrate stack has a characteristic dimension of about one half of a wavelength in the frequency spectrum of the mm-wave emission source, with the characteristic dimension between 1 mm and 7 mm, so that the cavity is dimensioned to define a resonant structure for at least some frequencies in the frequency spectrum of the mm wave source.

Multiple coupled cavities implemented in the substrate stack define one or more defined passbands and strong out-of-band rejection. The cavity geometry is configured using features formed by the photolithographic process, and the resonant cavity can include sidewalls not parallel along a dimension and an aspect ratio (length:width) that meets a specified minimum. Reflective material can be included on the top surface, bottom surface, and sidewalls to support the resonant cavity performance.

The disclosed configurations also include packaging and integration elements in which a lid substrate is bonded to a top wafer in the substrate stack and includes an input port and an output port. Optional tunability is described through deformable top and bottom plates using Si–PZT bimorphs, and example spectrometer configurations are described using tunable Gunn or IMPATT sources and Schottky or avalanche detectors.

Claims Coverage

Independent claim clm-00001 covers a photolithographically fabricated mm-wave passband filter formed from a substrate stack in which a resonant cavity is created by registration of photolithographically formed voids across adjacent substrates. The claim requires that the cavity has a characteristic dimension about one half of a wavelength in the frequency spectrum of the mm-wave emission source, and constrains that characteristic dimension between 1 mm and 7 mm. Dependent claims refine the cavity geometry, introduce reflective material, and add a lid substrate with input and output ports.

The coverage centers on a photolithographically fabricated mm-wave passband filter in which a resonant cavity is created by registering photolithographic voids across a substrate stack, with a characteristic half-wavelength dimension constrained to between 1 mm and 7 mm to define a resonant structure for frequencies in the mm-wave source spectrum. Dependent refinements further specify non-parallel sidewall geometry, high aspect ratio cavities, reflective materials on all cavity surfaces, and integration using a bonded lid substrate with input and output ports.

Stated Advantages

Documented Applications