A tunable duplexer circuit is described, wherein the frequency response as well as bandwidth and transmission loss characteristics can be dynamically altered, providing improved performance for transceiver front-end applications. The rate of roll-off of the frequency response can be adjusted to improve performance when used in duplexer applications. A method is described where the duplexer circuit characteristics are optimized in conjunction with a specific antenna frequency response to provide additional out-of-band rejection in a communication system. Dynamic optimization of both the duplexer circuit and an active antenna system is described to provide improved out-of-band rejection when implemented in RF front-end circuits of communication systems. Other features and embodiments are described in the following detailed descriptions.

A tunable duplexer circuit is described, wherein the frequency response as well as bandwidth and transmission loss characteristics can be dynamically altered, providing improved performance for transceiver front-end applications. The rate of roll-off of the frequency response can be adjusted to improve performance when used in duplexer applications. A method is described where the duplexer circuit characteristics are optimized in conjunction with a specific antenna frequency response to provide additional out-of-band rejection in a communication system. Dynamic optimization of both the duplexer circuit and an active antenna system is described to provide improved out-of-band rejection when implemented in RF front-end circuits of communication systems. Other features and embodiments are described in the following detailed descriptions.

The present disclosure is directed to a coil unit decoupling apparatus and a magnetic resonance system. The apparatus is connected to a first coil unit and a second coil unit in a magnetic resonance system, and is configured to separate, by using a distribution characteristic of a spatial quadrature field between the first coil unit and the second coil unit, a Helmholtz signal and an anti-Helmholtz signal from signals received from the first coil unit and the second coil unit, so as to implement decoupling between the first coil unit and the second coil unit. This facilitates the complexity of decoupling coil units being reduced.

The present disclosure is directed to a coil unit decoupling apparatus and a magnetic resonance system. The apparatus is connected to a first coil unit and a second coil unit in a magnetic resonance system, and is configured to separate, by using a distribution characteristic of a spatial quadrature field between the first coil unit and the second coil unit, a Helmholtz signal and an anti-Helmholtz signal from signals received from the first coil unit and the second coil unit, so as to implement decoupling between the first coil unit and the second coil unit. This facilitates the complexity of decoupling coil units being reduced.

A radio frequency module includes a switch circuit that includes selection terminals, a filter that allows the signal in the first frequency band to pass therethrough, a filter that allows the signal in the second frequency band to pass therethrough, a phase adjustment circuit that is connected to the selection terminal and the filter, and a phase adjustment circuit that is connected to the selection terminal and the filter. The filter includes an acoustic wave resonator that is formed on a substrate that has piezoelectricity. The filter includes an acoustic wave resonator that is formed on a substrate that has piezoelectricity. At least one of circuit elements that are included in the phase adjustment circuit is formed on the substrate. At least one of circuit elements that are included in the phase adjustment circuit is formed on the substrate.

A radio frequency module includes a switch circuit that includes selection terminals, a filter that allows the signal in the first frequency band to pass therethrough, a filter that allows the signal in the second frequency band to pass therethrough, a phase adjustment circuit that is connected to the selection terminal and the filter, and a phase adjustment circuit that is connected to the selection terminal and the filter. The filter includes an acoustic wave resonator that is formed on a substrate that has piezoelectricity. The filter includes an acoustic wave resonator that is formed on a substrate that has piezoelectricity. At least one of circuit elements that are included in the phase adjustment circuit is formed on the substrate. At least one of circuit elements that are included in the phase adjustment circuit is formed on the substrate.

A switch module includes a first terminal, first and second filters, and first and second switches. Impedance of the first filter for a signal in a stop band is capacitive. When the first switch is turned OFF, impedance of the first switch is capacitive, and impedance of the first filter seen from an end portion of the first switch connected to the first filter is not in a short state and impedance of the first filter seen from the first terminal is in an open state.

Disclosed is a microwave cavity resonator used as a phase change (phase modulation) to intensity change (intensity or amplitude modulation) converter. Certain aspects and embodiments include resonant circuits, such as a resistor, inductor and capacitor (RLC) circuit. Certain aspects and embodiments convert changes in phase to changes in output voltage to perform analog demodulation of a phase modulated microwave carrier. Certain aspects and embodiments use resonance when the reactive components of the circuit (capacitive and inductive components) are equal in magnitude and 180 degrees out of phase with one another, thereby cancelling out the reactance component of the circuit's impedance.

A switch module includes a first terminal, first and second filters, and first and second switches. Impedance of the first filter for a signal in a stop band is capacitive. When the first switch is turned OFF, impedance of the first switch is capacitive, and impedance of the first filter seen from an end portion of the first switch connected to the first filter is not in a short state and impedance of the first filter seen from the first terminal is in an open state.

The present disclosure provides a phase shifter including: a first substrate and a second substrate. The first substrate includes a reference electrode and a signal electrode, and the signal electrode includes a main structure and multiple branch structures. The second substrate includes multiple patch electrodes, and the multiple patch electrodes are arranged in a one-to-one correspondence with the multiple branch structures to form multiple variable capacitors. The phase shifter has a first region, and a second region and a third region which are respectively provided on two sides of the first region; and for any two of variable capacitors located on a same side of the first region, an overlap area of patch electrode and branch structure of a variable capacitor close to the first region is greater than or equal to that of a variable capacitor away from the first region.