Enhanced LC filter with tunable Q

A tunable electronic filter circuit comprising:

• an input terminal;
• an output terminal connected to the input terminal with a node therebetween;
• a variable capacitor coupled between the node and a common ground reference;
• an inductor coupled between the node and the common ground reference;
• a variable resistor coupled between the node and the common ground reference;
• a feedback control circuit coupled to the variable resistor, the feedback control circuit further operable to tune the variable resistor in order to calibrate a quality factor of the electronic filter circuit, wherein the feedback control circuit includes a quality factor calibration loop, wherein the quality factor calibration loop includes a peak detector;
• whereby when an input signal is applied to the input terminal, the electronic filter circuit passes an output signal to the output terminal which includes components of the input signal within a predetermined frequency bandwidth set by a predetermined frequency while substantially filtering out other components of the input signal.

An adjustable load circuit with variable reactance comprising:

• an input terminal;
• an output terminal connected to the input terminal with a node therebetween;
• a variable capacitor coupled between the node and a common ground reference;
• an inductor coupled between the node and the common ground reference;
• a resistor coupled between the node and the common ground reference;
• a control circuit coupled to the variable capacitor, the control circuit operable to tune the variable capacitor for varying a reactance of the load circuit;
• wherein the control circuit includes a quality factor calibration loop, wherein the quality factor calibration loop includes a peak detector;
• whereby when an input signal is applied to the input terminal, an output signal is generated at the output terminal which may be varied by varying the reactance of the load circuit.

An adjustable load circuit with variable resistance comprising:

• an input terminal;
• an output terminal connected to the input terminal with a node therebetween;
• a capacitor coupled between the node and a common ground reference;
• an inductor coupled between the node and the common ground reference;
• a variable resistor coupled between the node and the common ground reference;
• a control circuit coupled to the variable resistor, the control circuit further operable to tune the variable resistor for varying a resistance of the load circuit, wherein the control circuit includes a quality factor calibration loop, wherein the quality factor calibration loop includes a peak detector;
• whereby when an input signal is applied to the input terminal, an output signal is generated at the output terminal which may be varied by varying the resistance of the load circuit.

A method of controlling an adjustable load circuit including a variable capacitor and a variable resistor, the method comprising:

• adjusting the variable capacitor of the load circuit to adjust a reactance of the load circuit for the purpose of varying an output signal at the load circuit;
• and
• adjusting the variable resistor of the load circuit to adjust a resistance of the load circuit for the purpose of varying the output signal at the load circuit,
• feeding back a quality factor in a calibration loop, wherein the quality factor calibration loop includes a peak detector.