An LC filter arrangement includes a filter capacitor that connects the first output terminal to the second output terminal, a magnetic core, and a choke having a plurality of turns surrounding the magnetic core, and a first choke terminal and a second choke terminal. Each of the turns is formed by a separate conductor segment, at least partially surrounding the magnetic core. The LC filter arrangement is mounted on a circuit board and is electrically connected to a conductor track of the circuit board.

A balun includes: first wiring that has a first end connected to a first balanced line and a second end connected to a second balanced line; second wiring that has a grounded first end and a second end; third wiring that has a first end connected to the second end of the second wiring and a second end connected to an unbalanced line and is electromagnetically coupled to the second wiring; a first capacitor that has a first end connected to the first end of the third wiring and a grounded second end; and a second capacitor that has a first end connected to the second end of the third wiring and a grounded second end. The first wiring is electromagnetically coupled to at least one of the second wiring and the third wiring.

A balun includes: first wiring that has a first end connected to a first balanced line and a second end connected to a second balanced line; second wiring that has a grounded first end and a second end; third wiring that has a first end connected to the second end of the second wiring and a second end connected to an unbalanced line and is electromagnetically coupled to the second wiring; a first capacitor that has a first end connected to the first end of the third wiring and a grounded second end; and a second capacitor that has a first end connected to the second end of the third wiring and a grounded second end. The first wiring is electromagnetically coupled to at least one of the second wiring and the third wiring.

An antenna oscillator unit includes a radiator and a balun support. The radiator is fixed to the balun support and includes a plurality of low-frequency oscillator arms circumferentially distributed along the balun support. Each of the low-frequency oscillator arms includes two radiating sections connected to each other and a connecting section connecting the two radiating sections to form a closed loop. The two radiating sections are substantially perpendicular to each other. The antenna oscillator unit of some embodiments can avoid mutual coupling of signals from the antenna oscillator unit and an adjacent high-frequency oscillator and can improve the capability to radiate electromagnetic signals.

An antenna oscillator unit includes a radiator and a balun support. The radiator is fixed to the balun support and includes a plurality of low-frequency oscillator arms circumferentially distributed along the balun support. Each of the low-frequency oscillator arms includes two radiating sections connected to each other and a connecting section connecting the two radiating sections to form a closed loop. The two radiating sections are substantially perpendicular to each other. The antenna oscillator unit of some embodiments can avoid mutual coupling of signals from the antenna oscillator unit and an adjacent high-frequency oscillator and can improve the capability to radiate electromagnetic signals.

Impedance matching circuits, impedance matching elements, and radio communication circuits are provided in this disclosure. The impedance matching circuit may include a first impedance matching element which is configured to radio communication circuit may include a modulator configured to receive an unbalanced input signal from a first input, and couple the unbalanced input signal to a first output to match an impedance of the first output to a first impedance. It may further include a second impedance matching element coupled to the first input to receive the unbalanced input signal, the second impedance matching element configured to couple the unbalanced input signal to a second output to match an impedance of the second output to a second impedance. A terminal of the first output and a terminal of the second output may be coupled to provide a balanced output signal, and the coupling may match an output impedance of the impedance matching circuit based on the first impedance and the second impedance.

Impedance matching circuits, impedance matching elements, and radio communication circuits are provided in this disclosure. The impedance matching circuit may include a first impedance matching element which is configured to radio communication circuit may include a modulator configured to receive an unbalanced input signal from a first input, and couple the unbalanced input signal to a first output to match an impedance of the first output to a first impedance. It may further include a second impedance matching element coupled to the first input to receive the unbalanced input signal, the second impedance matching element configured to couple the unbalanced input signal to a second output to match an impedance of the second output to a second impedance. A terminal of the first output and a terminal of the second output may be coupled to provide a balanced output signal, and the coupling may match an output impedance of the impedance matching circuit based on the first impedance and the second impedance.

The invention discloses a power noise suppression circuit applied to a power system. The power noise suppression circuit comprises at least one power noise to heat converter and at least one anti-power noise transmitted unit. When a power noise within a specific frequency band enters the power noise suppression circuit, the power noise to heat converter converts the power noise to a thermal energy, and the anti-power noise transmitted unit reflects the power noise within the specific frequency band to the power noise to heat converter. Accordingly, the power noise within the specific frequency band can be suppressed and absorbed in the power noise suppression circuit, so as to maintain the stability of the power system.

Techniques are provided for a broadband microwave/millimeter-wave balanced-to-unbalanced transformer (balun). A balun implementing the techniques according to an embodiment includes a first impedance matching network configured to reduce insertion and return losses of a single-ended signal at a first port of the balun. The balun also includes a first planar bifilar coupled transmission line coupled to the first impedance matching network and configured to transform the single-ended signal into a differential signal. The balun further includes a second planar bifilar coupled transmission line coupled to the first bifilar coupled transmission line and configured to compensate for amplitude and phase imbalance induced on the differential signal by the first bifilar coupled transmission line. The balun further includes a second impedance matching network coupled to both planar bifilar coupled transmission lines and configured to reduce insertion and return losses of the differential signal at second and third ports of the balun.

Techniques are provided for a broadband microwave/millimeter-wave balanced-to-unbalanced transformer (balun). A balun implementing the techniques according to an embodiment includes a first impedance matching network configured to reduce insertion and return losses of a single-ended signal at a first port of the balun. The balun also includes a first planar bifilar coupled transmission line coupled to the first impedance matching network and configured to transform the single-ended signal into a differential signal. The balun further includes a second planar bifilar coupled transmission line coupled to the first bifilar coupled transmission line and configured to compensate for amplitude and phase imbalance induced on the differential signal by the first bifilar coupled transmission line. The balun further includes a second impedance matching network coupled to both planar bifilar coupled transmission lines and configured to reduce insertion and return losses of the differential signal at second and third ports of the balun.