High rejection wideband bandpass N-path filter

An N-path filter configured as a bandpass filter, the N-path filter comprising a plurality of branches selectively connected with a common node, each branch of the N-path filter comprising a switch connected in series with a generalized impedance converter circuit, wherein the generalized impedance converter circuit comprises:

• first, second, third, fourth, and fifth impedances connected in series;
• a first amplifier having a positive input, a negative input, and an output, wherein:
• the positive input of the first amplifier is connected with the first impedance;
• the negative input of the first amplifier is connected with a node between the second impedance and the third impedance;
• and
• the output of the first amplifier is connected with a node between the third impedance and the fourth impedance;
• and
• a second amplifier having a positive input, a negative input, and an output, wherein:
• the positive input of the second amplifier is connected with a node between the fourth impedance and the fifth impedance;
• the negative input of the second amplifier is connected with the node between the second impedance and the third impedance;
• and
• the output of the second amplifier is connected with a node between the first impedance and the second impedance.

A method for filtering a signal, comprising selectively connecting each of a plurality of branches of an N-path filter with a circuit node carrying the signal, each branch of the N-path filter comprising a switch connected in series with a generalized impedance converter circuit, wherein the selectively connecting comprises:

• connecting a first one of the plurality of branches of the N-path filter with the circuit node;
• disconnecting the first one of the plurality of branches of the N-path filter from the circuit node;
• and
• after the disconnecting, connecting a second one of the plurality of branches of the N-path filter with the circuit node.

A circuit for use in a device configured to wirelessly transmit or receive signals, the circuit comprising:

• a plurality of branches selectively connected with a common node in a signal path, each of the plurality of branches comprising:
• a bandpass response circuit;
• and
• a switch having a first terminal coupled to the common node and a second terminal coupled to one or more components of the bandpass response circuit,
• wherein at least one pair of the plurality of branches is coupled together at respective nodes disposed between the second terminal and at least one component of the bandpass response circuit of a respective branch of the at least one pair of the plurality of branches wherein the at least one pair of the plurality of branches is coupled together by a passive component.