Active feedback analog filters with coupled resonators
AssigneeAnlotek Limited
InventorJorgen Staal Nielsen
Life of this patent
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Abstract
A variable filter for an RF circuit has a signal loop comprising a signal input port and a signal output port, and a plurality of circuit elements connected within the signal loop. The plurality of circuit elements comprise a multi-pole resonator comprising a plurality of frequency tunable resonators and an adjustable scaling block that applies a gain factor. Adjacent frequency tunable resonators within the multi-pole resonator are reciprocally coupled. A controller is connected to tune the multi-pole resonator and to adjust the gain factor of the adjustable scaling block such that the signal loop generates a desired bandpass response.
Claims19
A variable filter for an RF circuit, comprising:
- a signal loop comprising a signal input port and a signal output port;
- a plurality of circuit elements connected within the signal loop, the plurality of circuit elements comprising:
- a multi-pole resonator comprising a first frequency tunable resonator having a first capacitance and a second frequency tunable resonator having a second capacitance, the first frequency tunable resonator being reciprocally coupled with the second frequency tunable resonator by a coupling capacitor;
- and
- an adjustable scaling block that applies a gain factor;
- and
- a controller that comprises instructions to tune the multi-pole resonator and to adjust the gain factor of the adjustable scaling block such that the signal loop generates a desired bandpass response with a desired center frequency.
A method of designing an RF bandpass filter, the method comprising the steps of:
- connecting a plurality of frequency tunable resonators such that adjacent frequency tunable resonators are reciprocally coupled by a coupling capacitor, wherein each frequency tunable resonator comprises an inductor and a tunable capacitor;
- and
- connecting the plurality of frequency tunable resonators and an adjustable scaling block that applies a gain factor in a signal loop, the signal loop comprising an input port, and an output port.
A method of controlling a variable filter, comprising the steps of:
- providing:
- a signal loop comprising a signal input port and a signal output port, a plurality of circuit elements being connected within the signal loop, the plurality of circuit elements comprising:
- a multi-pole resonator comprising a plurality of frequency tunable resonators, wherein adjacent frequency tunable resonators within the multi-pole resonator are reciprocally coupled by coupling capacitors, each frequency tunable resonator comprising an inductor and a capacitor;
- and
- an adjustable scaling block that applies a gain factor;
- and
- tuning the multi-pole resonator and adjusting the gain factor of the adjustable scaling block such that the signal loop generates a desired bandpass response having a desired center frequency.
Dependencies are inferred from the claim text.