Provided herein are apparatus and methods for reconfigurable directional couplers in an RF transceiver. Reconfigurable directional couplers can be reconfigured and designed to provide high directivity using configurable capacitors to effect a mutual coupling and using lumped components or delay lines to effect a phase shift. Depending on the embodiment, the reconfigurable directional coupler can include capacitors, inductors, and switching components. The coupler can be designed for multi-band operation with an adjustable coupling factor conducive to semiconductor process integration. The coupler can have variable phase shifters to achieve a desired level of directivity in the coupler.

An integrated circuit is a layered device, on a semiconductor substrate, which contains metal electrodes that sandwich a piezoelectric layer, followed by a magnetostrictive layer and a metal coil. The metal electrodes define an electrical port across which to receive an alternating current (AC) voltage, which is applied across the piezoelectric layer to cause a time-varying strain in the piezoelectric layer. The magnetostrictive layer is to translate the time-varying strain, received by way of a vibration mode from interaction with the piezoelectric layer, into a time-varying electromagnetic field. The metal coil, disposed on the magnetostrictive layer, includes a magnetic port at which to induce a current based on exposure to the time-varying electromagnetic field generated by the magnetostrictive layer.

A coupling circuit for power line communications includes a coupling transformer having first and second mutually coupled windings, with the first winding connectable to a power line. The second winding includes a pair of intermediate taps with one or more tuning inductor therebetween. The inductor or inductors are set between a first portion and a second portion of the second winding of the coupling transformer. A switch member is provided coupled with the inductor. The switch member is selectively actuatable to short-circuit the inductor.

Provided is a microwave filter system having a feedback structure. The microwave filter system may include an input hybrid coupler configured to output first output signals having a phase difference with respect to an input signal; filters disposed to be in parallel with an output end of the input hybrid coupler, and configured to filter the first output signals; and an output hybrid coupler configured to output second output signals having a phase difference with respect to each of signals filtered through the filters. An output signal of the output hybrid coupler is applied to an input end of the input hybrid coupler along a feedback path.

A radiofrequency filter utilizing a common mode choke both as a traditional common mode choke as well as the inductance in a low pass filter. Filter topology as well as component selection is optimized for wide band operation. Common mode chokes allow differential currents to pass with little attenuation while common mode currents are effectively presented with an inductance in the common current path. This inductance is used in a low pass filter configuration to present an even higher attenuation to common mode currents. The use of multiple chokes and/or differing core materials contributes to wider band operation without pronounced resonances. The capacitance used in the low pass filter is connected in a way as to reduce its effect on the data signals while still being effective in filtering.

Disclosed is a two-capacitor-based filter design method comprising: determining a frequency f.sub.1 and a fractional bandwidth ratio FBW; selecting a first and a second capacitors according to f.sub.1 and FBW, in which a resonant frequency f.sub.C1 of the first capacitor is equal to f.sub.1(1NFBW), a resonant frequency f.sub.C2 of the second capacitor is equal to f.sub.1(1+MFBW), and each of N and M is a positive number less than one; and determining a length of a first transmission line according to f.sub.C1 and a signal speed, and determining a length of a second transmission line according to f.sub.C2 and the signal speed. The first capacitor is coupled between a center of the first transmission line and ground, the second capacitor is coupled between a center of the second transmission line and ground, and the first and second transmission lines are connected in series.

Provided herein are methods of reconfiguring directional couplers in an RF transceiver. The methods can include designing and reconfiguring the directional couplers to provide high directivity and a desired coupling factor using configurable capacitors to effect a mutual coupling and using lumped components or delay lines to effect a phase shift. The reconfigurable directional couplers can be designed for multi-band operation with an adjustable coupling factor conducive to semiconductor process integration. The reconfigurable directional couplers can have variable phase shifters to achieve a desired level of directivity in the coupler. In various examples, the methods include monitoring the frequency of power signals received by the reconfigurable directional couplers, and adjusting the configurable capacitors and/or variable phase shifters to maintain desired directivity and coupling factors over multi-band operation of the reconfigurable directional couplers.

[Object] To propose a wireless communication apparatus capable of realizing separation of transmission signals and reception signals with a low power consumption and a small size. [Solution] Provided is a wireless communication apparatus including: a gyrator that includes at least four terminals; a single-phase differential converter that mutually converts single-phase signals and differential signals; a low-noise differential amplifier that amplifies reception signals that the gyrator outputs; and a differential power amplifier that amplifies transmission signals to be output to the gyrator. The gyrator transmits signals from a first terminal and a second terminal in the direction of a third terminal and a fourth terminal. Any of the single-phase differential converter, the low-noise amplifier, and the power amplifier are connected to the first terminal and second terminal, the third terminal and fourth terminal, the first terminal and third terminal, and the second terminal and fourth terminal of the gyrator.

Provided herein are apparatus and methods for reconfigurable directional couplers in an RF transceiver. Reconfigurable directional couplers can be reconfigured and designed to provide high directivity using configurable capacitors to effect a mutual coupling and using lumped components or delay lines to effect a phase shift. Depending on the embodiment, the reconfigurable directional coupler can include capacitors, inductors, and switching components. The coupler can be designed for multi-band operation with an adjustable coupling factor conducive to semiconductor process integration. The coupler can have variable phase shifters to achieve a desired level of directivity in the coupler.

Reflectionless transmission line filters, as well as a method for designing such filters is disclosed. These filters preferably function by absorbing the stop-band portion of the spectrum rather than reflecting it back to the source, which has significant advantages in many different applications. The insertion of additional transmission line sections that change the phase response of the circuit without altering the amplitude response preferably allows follow-up transmission line identities to be applied in order to arrive at a more easily manufacturable filter topology. This facilitates their application over a higher frequency range the solely lumped-element circuits.