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US 10,651,824 B2Granted
Tunable filter for RF circuits
AssigneeEthertronics, Inc.
InventorLaurent Desclos
Life of this patent
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Abstract
A tunable filter is described where the frequency response as well as bandwidth and transmission loss characteristics can be dynamically altered, providing improved performance for transceiver front-end tuning applications. The rate of roll-off of the frequency response can be adjusted to improve performance when used in duplexer applications. The tunable filter topology is applicable for both transmit and receive circuits. A method is described where the filter characteristics are adjusted to account for and compensate for the frequency response of the antenna used in a communication system.
Claims10
A communication system, comprising:
- at least one tunable filter circuit capable of dynamic adjustment of a frequency, bandwidth, or transmission loss characteristics;
- a processor;
- a lookup table (LUT) resident in the processor or other memory cell;
- wherein the at least one tunable filter circuit comprises:
- a first operational amplifier comprising a non-inverting input and an output thereof;
- a second operational amplifier comprising a non-inverting input and an output thereof,
- the output of the first operational amplifier connected to the non-inverting input of the second operational amplifier at an output of the at least one tunable filter circuit;
- the output of the second operational amplifier connected to the non-inverting input of the first operational amplifier at an input of the at least one tunable filter circuit;
- wherein the at least one tunable filter circuit further comprises:
- a variable capacitor connected in shunt between the non-inverting input of the first operational amplifier and ground;
- wherein the variable capacitor is configured to receive control signals for changing a tuning state of the variable capacitor;
- and
- wherein the at least one tunable filter circuit is tuned by changing the tuning state of the variable capacitor.
10 more elements
Dependencies are inferred from the claim text.