Patent ID: 8686788

Claim:
A filter circuit, comprising: an amplifier having a positive output port and a negative output port, said amplifier receiving an input signal at an input port and generating a differential output signal at said positive output port and said negative output port; a first resonator having first and second terminals, wherein said first terminal is connected to said positive output port of said amplifier, said first resonator having a series resonant frequency and a parallel resonant frequency; a second resonator having first and second terminals, wherein said first terminal is connected to said negative output port of said amplifier, the second resonator having a series resonant frequency and a parallel resonant frequency such that the series resonant frequency of one of the first and second resonators is substantially equal to the parallel resonant frequency of the other of the first and second resonators; said second terminals of the first and second resonators being electrically coupled at a connection to sum signals passing therethrough; and a buffering device of substantially zero input impedance for receiving the electrically coupled signals passing through the first and second resonators and outputting a filtered signal.