Abstract: A folded Marchand Balun includes a first, a second, a third port, and a first transmission line being folded into a first and second intermediate transmission lines, the first intermediate transmission line disposed on a first signal plane and electrically connected through metal vias to the second intermediate transmission line disposed on a second signal plane. The first transmission line has one end as the first port and an opposite end as an open circuit. The Balun includes a second transmission line disposed on the first signal plane and is adjacent to the first intermediate transmission line. The second transmission line has one end as the second port and an opposite end grounded. The Balun includes a third transmission line disposed on the second signal plane and adjacent to the second intermediate transmission line. The third transmission line has one end as the third port and an opposite end grounded.

Abstract: An amplifier includes a first and a second differential input ports, and a single-ended output port. The amplifier includes a first and a second transistors, each having a gate, source, and drain terminals. The source terminals are coupled to a reference plane and the gate terminals are coupled to the respective first and second differential input ports. The amplifier includes a Balun having a primary and a secondary transformer winding, the primary transformer winding having one end coupled to the drain terminal of the first transistor, an opposite end coupled to the drain terminal of the second transistor, and a center tap coupled to a bias voltage, and the secondary transformer winding is adjacent to the primary transformer winding and having one end coupled to the single-ended output port and an opposite end open circuited. An electromagnetic field generated at the primary induces a signal at the secondary transformer winding.

Abstract: A folded Marchand Balun includes a first, a second, a third port, and a first transmission line being folded into a first and second intermediate transmission lines, the first intermediate transmission line disposed on a first signal plane and electrically connected through metal vias to the second intermediate transmission line disposed on a second signal plane. The first transmission line has one end as the first port and an opposite end as an open circuit. The Balun includes a second transmission line disposed on the first signal plane and is adjacent to the first intermediate transmission line. The second transmission line has one end as the second port and an opposite end grounded. The Balun includes a third transmission line disposed on the second signal plane and adjacent to the second intermediate transmission line. The third transmission line has one end as the third port and an opposite end grounded.

Abstract: A circuit antenna includes an active device, and first and second antennas. The first antenna is connected to an input port of the active device. The first antenna has a first radiation field at an operating frequency of the circuit antenna. The second antenna is connected to an output port of the active device. The second antenna has a second radiation field at the operating frequency. The active device is positioned within the first and second radiation fields to experience an input load matching impedance at the input port and an output load matching impedance at the output port, due to the first and second radiation fields.

Abstract: A circuit antenna includes an active device, and first and second antennas. The first antenna is connected to an input port of the active device. The first antenna has a first radiation field at an operating frequency of the circuit antenna. The second antenna is connected to an output port of the active device. The second antenna has a second radiation field at the operating frequency. The active device is positioned within the first and second radiation fields to experience an input load matching impedance at the input port and an output load matching impedance at the output port, due to the first and second radiation fields.