According to one embodiment, there is provided a magnetic coupling device including a first coil, a second coil, a third coil, a fourth coil, a first constant-potential node and a second constant-potential node. The second coil is electrically connected with one end of the first coil and wound in a direction opposite to a direction in which the first coil is wound. The third coil faces the first coil. The fourth coil faces the second coil. The first constant-potential node is electrically connected with one end of the third coil. The second constant-potential node is electrically connected with one end of the fourth coil.

According to one embodiment, there is provided a magnetic coupling device including a first coil, a second coil, a third coil, a fourth coil, a first constant-potential node and a second constant-potential node. The second coil is electrically connected with one end of the first coil and wound in a direction opposite to a direction in which the first coil is wound. The third coil faces the first coil. The fourth coil faces the second coil. The first constant-potential node is electrically connected with one end of the third coil. The second constant-potential node is electrically connected with one end of the fourth coil.

Techniques are disclosed for filtering a radio frequency (RF) signal using an N-path bandstop filter with an extended, spurious-free upper passband. In an embodiment, a bandstop filter includes a bank of three switched capacitors in series with the RF signal path through the filter, in contrast to 4- or 8-capacitor banks or other bandstop filters where N is a power of 2. In this 3-path example configuration, an undesirable spurious bandstop notch at the 3.sup.rd and 5.sup.th harmonics of the clock frequency are eliminated or substantially reduced, improving performance of the filter in the desired passbands while preserving the notch in the desired stopband at high RF signal frequencies. Another N-path bandstop filter embodiment includes a bridged T-coil circuit, which absorbs a shunt capacitance of the bandstop filter into the bridged T-coil circuit.

An integrated isolator circuit for isolating receiver and transmitter in a Time-Division Duplex transceiver is disclosed. The integrated isolator circuit comprises a first node, a second node and a third node. The integrated isolator circuit further comprises a first capacitor connected in series with a first switch and connected between the first and second nodes. The integrated isolator circuit further comprises a first inductor connected between the first and second nodes and a second capacitor connected between the second node and the third node. The first switch has an on state and an off state, and the integrated isolator circuit is configured to have a different impedance at a certain operating frequency by controlling the state of the first switch.

A phase shifter capable of improving phase accuracy by a simple method is provided. The phase shifter includes a hybrid coupler circuit including inductors with mutual inductances, an amplifying circuit, an impedance matching circuit provided between the hybrid coupler circuit and the amplifying circuit. The impedance matching circuit includes a first resistance element connected to an output node of the hybrid coupler circuit, a capacitance element connected between the first resistance element and the ground line in series, another inductor connected in parallel with the first resistance element, and a second resistance element provided between the inductor and the ground line in series.

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.

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.

Circuits and methods for an amplifier (particularly LNAs) that achieve wideband output impedance matching and high gain while simultaneously rejecting out-of-band (OOB) harmonic frequencies. Some embodiments allow multiple modes of operation to allow selection of gain versus linearity characteristics. One aspect of the present invention is improvement of the linearity and sensitivity of a whole RF front end (RFFE) receiver chain by suppressing OOB gain within an LNA component at higher order harmonic frequencies. Another aspect of the present invention are new wideband and ultra-wideband LNA load circuits that, while achieving high frequency OOB rejection, maintain in-band high gain and wideband output impedance matching at the same time. Yet another aspect of the present invention are new ultra-wideband LNA output impedance matching circuits.

Circuits and methods for an amplifier (particularly LNAs) that achieve wideband output impedance matching and high gain while simultaneously rejecting out-of-band (OOB) harmonic frequencies. Some embodiments allow multiple modes of operation to allow selection of gain versus linearity characteristics. One aspect of the present invention is improvement of the linearity and sensitivity of a whole RF front end (RFFE) receiver chain by suppressing OOB gain within an LNA component at higher order harmonic frequencies. Another aspect of the present invention are new wideband and ultra-wideband LNA load circuits that, while achieving high frequency OOB rejection, maintain in-band high gain and wideband output impedance matching at the same time. Yet another aspect of the present invention are new ultra-wideband LNA output impedance matching circuits.

According to one embodiment, there is provided a magnetic coupling device including a first coil, a second coil, a third coil, a fourth coil, a first constant-potential node and a second constant-potential node. The second coil is electrically connected with one end of the first coil and wound in a direction opposite to a direction in which the first coil is wound. The third coil faces the first coil. The fourth coil faces the second coil. The first constant-potential node is electrically connected with one end of the third coil. The second constant-potential node is electrically connected with one end of the fourth coil.