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AssigneeMotorola, Inc.
InventorsAristotelis Arvanitis, Stanley Malinowski, Craig P. Smith, deceased, by Paul N. Page, administrator
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A dual-coupled monolithic crystal element is connected to a crystal filter to bypass signals of a predetermined frequency which are applied through the filter. The shunt connected crystal element can be used with a bandpass filter to bypass frequencies at which the crystal filter produces a spurious response so that such frequencies will not appear in the filter output. Alternatively, the monolithic element can be selected to bypass frequencies adjacent the edges of a band which is selected, to provide sharp attenuation at the edges of the band thereby providing a very steep filter characteristic. The monolithic element includes a flat quartz wafer with electrodes provided on both sides at two separate portions of the wafer to form two resonant portions coupled through the wafer. The electrodes of one portion are connected across the input or the output of the crystal filter, and both electrodes of the other resonating portions are grounded.
A shunt circuit for use with an electrical filter having an input signal conductor, an output signal conductor, a reference potential and which has a predetermined response characteristic, for bypassing signals of a predetermined frequency band which are applied between said signal conductor and said reference potential, including in combination,
A circuit for use with an electrical filter coupled between an input signal conductor an output signal conductor and a reference potential, and which includes at least one crystal and has a desired frequency pass characteristic and an undesired pass characteristic at a predetermined frequency resulting from spurious responses of the crystal, such circuit passing undesired signals at said predetermined frequency and including in combination,
A circuit for use with an electrical filter having an input signal conductor and an output signal conductor and which is coupled to a reference potential, and which includes at least one crystal and has a desired bandpass characteristic and undesired pass characteristics at first and second predetermined frequencies adjacent the opposite edges of the desired passband, such circuit bypassing signals at said predetermined frequencies and including in combination,
Dependencies are inferred from the claim text.