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US 8,941,443 B1Granted
Electronically tuned cavity filter
AssigneeRockwell Collins, Inc.
InventorRobert Newgard
Life of this patent
Estimating the term…
Abstract
A cavity filter having a piezoelectric tuning element is tuned by determining a desired oscillating frequency for the piezoelectric tuning element and applying that frequency through a phase-locked loop. The phase-locked loop maintains the piezoelectric tuning element at the desired frequency.
Claims18
An apparatus for tuning a cavity filter comprising:
- a membrane assembly comprising a piezoelectric tuning element configured to form a portion of the cavity filter;
- and
- a phase-locked loop circuit comprising:
- a phase-locked loop control system connected to the piezoelectric tuning element;
- a VCO gain element connected to the phase-locked loop control system;
- and
- a LC resonator connected to the VCO gain element, the LC resonator comprising:
- a tank coil, connected to the VCO gain element;
- and
- a capacitive disk connected to the tank coil,
- wherein:
- the VCO gain element, tank coil, capacitive disk and the piezoelectric tuning element form a resonator capacitor,
- the phase-locked loop control system is configured to apply a control signal to the piezoelectric tuning element,
- the LC resonator is configured to generate an oscillating signal in the VCO gain element, and
- the phase-locked loop circuit is configured to lock based on a phase difference between the reference signal and the oscillating signal.
12 more elements
An apparatus for tuning a plurality of cavity filters comprising:
- a membrane assembly comprising a plurality of piezoelectric tuning elements, each piezoelectric tuning element configured to form a portion of one of the plurality of cavity filters;
- and
- a plurality of phase-locked loop circuits, each phase-locked loop circuit comprising:
- a phase-locked loop control system connected to one of the plurality of piezoelectric tuning elements;
- a VCO gain element connected to the phase-locked loop control system;
- a LC resonator connected to the VCO gain element;
- and
- a capacitive disk connected to the LC resonator,
- wherein:
- each capacitive disk and piezoelectric tuning element comprise a resonator capacitor;
- each phase-locked loop control system is configured to apply a control signal to the one of the piezoelectric tuning elements,
- each LC resonator is configured to generate an oscillating signal in the VCO gain element,
- each phase detector element is configured to measure a phase difference between a reference signal and the oscillating signal, and
- each of the plurality of phase-locked loop circuits is configured to operate independently of each of the other of the plurality of phase-locked loop circuits.
11 more elements
A method of tuning a cavity filter comprising:
- applying a control voltage to a piezoelectric tuning element;
- generating an oscillator frequency in a voltage-controlled oscillator including the piezoelectric tuning element based on a piezoelectric effect of the piezoelectric tuning element;
- comparing a phase of an oscillator frequency with a phase of a reference frequency to produce a phase difference voltage
- generating a control signal based on the phase difference voltage;
- and
- altering the oscillator frequency based on control signal,
- wherein applying the control voltage to a piezoelectric tuning element;
- generating the oscillator frequency;
- comparing a phase of an oscillator frequency with a phase of a reference frequency;
- generating the control signal;
- and altering the oscillator frequency constitute a feedback loop to tune the cavity filter to a desired center frequency.
8 more elements
Dependencies are inferred from the claim text.