Multi-band tunable resonant circuit

A tunable low noise amplifier circuit comprising:

• a tunable resonant circuit including:
• at least one transmission line having an inductance;
• a plurality of switchable capacitors configured to be switched into and out of the tunable resonant circuit in response to a first control signal;
• and
• at least one variable capacitor that can be varied in response to a second control signal;
• wherein a center resonant frequency of the tunable resonant circuit is electronically tunable responsive to the first and second control signals that control a first capacitance value of the plurality of switchable capacitors and a second capacitance value of the at least one variable capacitor;
• and
• a low noise amplifier coupled to the tunable resonant circuit;
• wherein a reactance of the tunable resonant circuit is tuned so as to balance a reactance of the low noise amplifier and match an input impedance of the low noise amplifier to a load.

A method of tuning a resonant circuit over a plurality of frequency bands and within one frequency band of the plurality of frequency bands, the method comprising:

• providing an inductance;
• providing a first capacitance value and a second capacitance value each in parallel with the inductance to provide the resonant circuit;
• selecting the first capacitance value in response to a first control signal to tune a resonant frequency signal of the resonant circuit to the one frequency band;
• selecting the second capacitance value in response to a second control signal to tune the resonant frequency within the one frequency band;
• and
• matching an input impedance of a low noise amplifier to a load by:
• coupling the resonant circuit to the low noise amplifier;
• and
• tuning a reactance of the resonant circuit so as to balance a reactance of the low noise amplifier and match an input impedance of the low noise amplifier to the load.