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Title: Active filter and phase-locked loop using same
Abstract:
A second order filter signal is derived in response to a phase comparison of two signals by selecting an input voltage from a reference voltage, a first voltage potential higher than the reference voltage, and a second voltage potential lower than the reference voltage depending on the phase error of the two signals. The input signal is applied to a loop filter including a non-inverting integrator and to a feed forward circuit. The outputs of the amplifier and feed forward circuit are summed and applied to an output terminal as the second order filter signal. An improved phase locked oscillator circuit is provided in which a digital phase comparator drives an active loop filter including a feed forward circuit and a non-inverting integrator.
Other info: Inventors: Fazakerly, William B. (Saratoga, CA, US) Hafeman, Daniel R. (Sunnyvale, CA, US) Application Number: 933170 Filing Date: 1978-08-14 Publication_date: 1980-06-17 Assignee: Scientific Micro Systems, Inc. (Mountain View, CA) Primary Class(es): 331/17 327/552, 331/25 Other Classes: US Patent Ref:
Other Refs:
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