METHODS AND APPARATUSES FOR IMPLEMENTING VARIABLE BANDWIDTH RF TRACKING FILTERS FOR RECONFIGURABLE MULTI-STANDARD RADIOS
First Claim
1. A variable-bandwidth filter comprising:
- a first filter branch in parallel with a second filter branch;
the first filter branch comprising a first resistance in series with an input and a first output, and a first plurality of N parallel paths across the first output, each of respective paths of the first plurality of N parallel paths comprising a corresponding capacitor in series with a corresponding switch and a common terminal;
the second filter branch comprising a second resistance in series with the input and a second output, and a second plurality of N parallel paths across the second output, each of respective paths of the second plurality of N parallel paths comprising a corresponding resistor-capacitor (RC) network in series with a corresponding switch and a common terminal;
a clock for tuning the first and second filter branches to a center frequency by controlling the switches of the first and second filter branches to switch at the center frequency;
a combiner for producing a difference signal comprising a difference between the output of the first filter branch and the output of the second filter branch;
the difference signal providing a filter output for the variable bandwidth filter wherein the filter bandwidth is adjustable with reference to a center frequency, the filter bandwidth being adjustable by changing a value of at least one resistor or at least one capacitor in one or more of the first filter branch or the second filter branch.
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Accused Products
Abstract
A variable bandwidth filter comprises a first filter branch in parallel with a second filter branch. The first filter branch comprises a first resistance in series with an input and a first output, and N parallel paths across the first output, each path comprising a corresponding capacitor in series with a corresponding switch and a common terminal. The second filter branch comprises a second resistance in series with the input and a second output, and N parallel paths across the second output, each path comprising an RC network in series with a switch and a common terminal. A clock tunes the first and second filter branches to a center frequency by controlling the switches of the first and second filter branches. A combiner produces a difference signal comprising a difference between the output of the first filter branch and the output of the second filter branch to provide a filter output having an adjustable bandwidth with reference to a center frequency. The bandwidth is adjusted by changing a value of at least one resistor or at least one capacitor in one or more of the first filter branch or the second filter branch.
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Citations
20 Claims
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1. A variable-bandwidth filter comprising:
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a first filter branch in parallel with a second filter branch; the first filter branch comprising a first resistance in series with an input and a first output, and a first plurality of N parallel paths across the first output, each of respective paths of the first plurality of N parallel paths comprising a corresponding capacitor in series with a corresponding switch and a common terminal; the second filter branch comprising a second resistance in series with the input and a second output, and a second plurality of N parallel paths across the second output, each of respective paths of the second plurality of N parallel paths comprising a corresponding resistor-capacitor (RC) network in series with a corresponding switch and a common terminal; a clock for tuning the first and second filter branches to a center frequency by controlling the switches of the first and second filter branches to switch at the center frequency; a combiner for producing a difference signal comprising a difference between the output of the first filter branch and the output of the second filter branch;
the difference signal providing a filter output for the variable bandwidth filter wherein the filter bandwidth is adjustable with reference to a center frequency, the filter bandwidth being adjustable by changing a value of at least one resistor or at least one capacitor in one or more of the first filter branch or the second filter branch. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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12. A method comprising:
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providing a variable-bandwidth filter comprising a first filter branch in parallel with a second filter branch;
the first filter branch comprising a first resistance in series with an input and a first output, and a first plurality of N parallel paths across the first output, each of respective paths of the first plurality of N parallel paths comprising a corresponding capacitor in series with a corresponding switch and a common terminal; and
the second filter branch comprising a second resistance in series with the input and a second output, and a second plurality of N parallel paths across the second output, each of respective paths of the second plurality of N parallel paths comprising a corresponding resistor-capacitor (RC) network in series with a corresponding switch and a common terminal;adjusting the variable-bandwidth filter by using a clock to tune the first and second filter branches to a center frequency by controlling the switches of the first and second filter branches to switch at the center frequency; producing a difference signal comprising a difference between the output of the first filter branch and the output of the second filter branch;
the difference signal providing a filter output for the variable-bandwidth filter having an adjustable filter bandwidth with reference to a center frequency; andadjusting the filter bandwidth by changing a value of at least one resistor or at least one capacitor in one or more of the first filter branch or the second filter branch. - View Dependent Claims (13, 14, 15, 16, 17, 18, 19, 20)
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Specification