An apparatus comprises a first circuit and a second circuit. The first circuit generally comprises differential symmetric band extension circuitry. The second circuit generally comprises coupled inductor coils configured to convert between differential and single-ended signal formats.

Embodiments relate to a transformer-based impedance matching network that may dynamically change its characteristic impedance by engaging different inductor branches on a primary side and optionally, on the secondary side. A primary side transformer circuit includes a primary inductor (311) and secondary inductor (321) configured to provide impedance matching over a first frequency band. One or more additional inductor branches (314A, 314B, are switchably coupled to either or both of the primary and secondary inductors to modify the impedance matching characteristics over additional operating frequencies. One or more LC filter branches (321, 322, 326, 327, 336, 330) can be included at the output of the secondary side to filter harmonic frequencies in each of the operating frequency bands.

An apparatus comprises a first circuit and a second circuit. The first circuit generally comprises differential symmetric band extension circuitry. The second circuit generally comprises coupled inductor coils configured to convert between differential and single-ended signal formats.

Provided are a device, a differential signal line processing method and a differential signal line processing apparatus. The device includes a first component and a second component; the first component and the second component perform signal transmission via multiple sets of differential signal lines; the device further includes at least one common-mode filter, each common-mode filter of the at least one common-mode filter being serially connected between the first component and the second component via one set of differential signal lines, and a group delay of the each common-mode filter being adopted for adjusting a delay of signal transmission on the one set of differential signal lines connected to the common-mode filter.

An apparatus includes an RF apparatus, and a wideband multi-band matching balun. The wideband multi-band matching balun includes a multi-band balun, which includes at least one three-element frequency-dependent resonator (TEFDR). The wideband multi-band matching balun further includes a differential-to-differential matching circuit coupled to the RF apparatus. The differential-to-differential matching circuit includes at least one TEFDR.

A small-sized balance filter includes an unbalanced terminal and two pairs of balanced terminals and has a low signal insertion loss. An unbalanced terminal, a first balanced terminal including first and second terminals, and a second balanced terminal Rx including first and second terminals are provided. An unbalanced-side inductor is provided between the unbalanced terminal and the ground, first balanced-side inductors are provided between the first and second terminals of the first balanced terminal, second balanced-side inductors are provided between the first and second terminals of the second balanced terminal, and the unbalanced-side inductor is electromagnetic-field-coupled to each of the first and second balanced-side inductors.

A balun circuit is disclosed. The balun circuit has an unbalanced port and a balanced port, wherein the balanced port comprises a first terminal, and a second terminal. The balun circuit further comprises a main line having a first end and a second end, the first end being coupled to the unbalanced port. Moreover, the balun circuit comprises a first sub-line electromagnetically coupled to the main line, the first sub-line having a first end and a second end, wherein the first end of the first sub-line is coupled to the first terminal of the balanced port. The balun circuit further comprises a second sub-line electromagnetically coupled to the main line, the second sub-line having a first end and a second end, wherein the first end of the second sub-line is coupled to the second terminal of the balanced port.

An apparatus includes an RF apparatus, and a wideband multi-band matching balun. The wideband multi-band matching balun includes a multi-band balun, which includes at least one three-element frequency-dependent resonator (TEFDR). The wideband multi-band matching balun further includes a differential-to-differential matching circuit coupled to the RF apparatus. The differential-to-differential matching circuit includes at least one TEFDR.

An apparatus includes a radio-frequency (RF) apparatus, and a multi-band matching balun coupled to the RF apparatus. The multi-band matching balun including a plurality of capacitors and a plurality of inductors. None of the plurality of capacitors and none of the plurality of inductors is variable or tunable.

A balun includes an unbalanced port, a first balanced port, a second balanced port, a main line, a subline, a capacitor, and an impedance matching section. The subline is configured to be electromagnetically coupled to the main line. The main line has a first end and a second end opposite to each other. The subline has a first end and a second end opposite to each other. The capacitor is provided between the first end of the main line and the unbalanced port. The impedance matching section is provided between the second end of the subline and the second balanced port. The second end of the main line is connected to a ground. The first end of the subline is connected to the first balanced port.