Bridge-T reflectionless bandstop filter

A method of filtering a signal, said method comprising:

• receiving, at an input port, an oscillating signal within a frequency band;
• providing the received oscillating signal to a series bandpass resonator in electrical connection with the input port and an output port;
• providing the received oscillating signal additionally to a first capacitor electrically connected with the input port;
• providing a capacitor-filtered oscillating signal to a bandstop resonator electrically connected with the first capacitor and ground;
• and
• providing a bandstop-filtered oscillating signal to a second capacitor electrically connected with the bandstop resonator and the output port,
• wherein the series bandpass resonator comprises a first bandpass impedance element, a bandpass capacitor and a second bandpass impedance element arranged in series between the input port and the output port,
• wherein the bandstop resonator comprises a first bandstop impedance element, a bandstop capacitor and a second bandstop impedance element arranged in series between the first capacitor and ground,
• wherein the series bandpass resonator comprises a bandpass resonator impedance magnitude and a bandpass impedance phase,
• wherein the combination of the first capacitor, the bandstop resonator and the second capacitor comprises a bandstop impedance magnitude and a bandstop impedance phase,
• wherein the bandpass resonator impedance magnitude is substantially equal to the bandstop impedance magnitude,
• wherein the bandpass resonator impedance phase is substantially 180° out of phase with the bandstop impedance phase, and
• wherein the series bandpass resonator, the first capacitor, the bandstop resonator and the second capacitor operate as band stop for a predetermined frequency within the frequency band.

A bandstop filter comprising:

• an input port operable to receive an oscillating signal within a frequency band;
• an output port;
• a series bandpass resonator in electrical connection with said input port and said output port;
• a first capacitor electrically connected with said input port and said series bandpass resonator;
• a bandstop resonator electrically connected with said first capacitor and ground;
• and
• a second capacitor electrically connected with said bandstop resonator and said output port,
• wherein said series bandpass resonator comprises a first bandpass impedance element, a bandpass varactor and a second bandpass impedance element arranged in series between said input port and said output port,
• wherein said bandstop resonator comprises a first bandstop impedance element, a bandstop varactor and a second bandstop impedance element arranged in series between said first capacitor and ground,
• wherein said series bandpass resonator comprises a bandpass resonator impedance magnitude and a bandpass impedance phase,
• wherein the combination of said first capacitor, said bandstop resonator and said second capacitor comprises a bandstop impedance magnitude and a bandstop impedance phase,
• wherein the bandpass resonator impedance magnitude is substantially equal to the bandstop impedance magnitude,
• wherein the bandpass resonator impedance phase is substantially 180° out of phase with the bandstop impedance phase, and
• wherein said series bandpass resonator, said first capacitor, said bandstop resonator and said second capacitor operate as band stop for a predetermined frequency within the frequency band.