In accordance with an embodiment, a method of operating an RF system includes filtering a first wideband RF signal using a wideband filter bank. Filtering the first RF signal includes separating the first wideband RF signal into frequency cluster signals, where each frequency cluster signal of the frequency cluster signals includes different frequency ranges, the first wideband RF signal includes multiple RF bands, and each of the different frequency ranges comprises a plurality of RF bands of the multiple RF bands. The method further includes band stop filtering at least one of the frequency cluster signals to produce a band stopped frequency cluster signal.

Aspects of this disclosure relate to a radio frequency filter with two pass bands. The RF filter employs a first RF bandpass filter coupled to a common RF input and a common RF output. The RF filter further employs a second RF bandpass filter coupled to the common RF input and the common RF output. A first RF pass band of the first RF bandpass filter and a second RF pass band of the RF second bandpass filter are overlapping RF pass bands. Related methods and wireless communication devices are also disclosed.

A new demodulator with consistent sensibility to signals received from different directions, low power consumption, and low manufacturing cost is provided. The demodulator may include a first demodulator branch and a second demodulator branch electrically connected in parallel, and a DC circuit to provide DC power to the demodulator. The DC circuit has a first diode and a second diode electrically connected in series between a DC power supply Vcc and the ground. The second demodulator branch can share a low pass filter and a DC blocking capacitor of the first demodulator branch for example, and can multiplex or reuse a bias current from the first demodulator branch.

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 notch filter includes a first inductor coupled between an input node and an output node, a dual-resonator structure coupled between the input node and the output node, and a second inductor coupled between the dual-resonator structure and ground, and a bandpass filter includes a capacitor coupled between an input node and an output node, and a dual-resonator structure coupled between the input node, the output node, and ground.

A multiplexer includes a first filter circuit including a pass band that is a first frequency band, a second filter circuit including a pass band that is a second frequency band, and an additional circuit. The first filter circuit includes a first terminal connected to a common terminal and a second terminal connected to a first input/output terminal. The second filter circuit includes a third terminal connected to the common terminal and a fourth terminal connected to a second input/output terminal. The additional circuit is connected to the fourth terminal and one of the first and second terminals and includes a series-arm circuit on a series-arm path connecting the fourth terminal to the one of the terminals and a parallel-arm circuit on a parallel-arm path connecting the series-arm path to the ground. The parallel-arm circuit includes only an inductor, a capacitor, or an LC parallel-arm resonant circuit in series with the parallel-arm path.

A trap filter includes a first inductor, a second inductor, and a capacitor. A first end of the first inductor extends to a first connection portion, a third end of the second inductor is connected to a second end of the first inductor, and a fourth end extends to a second connection portion. The capacitor is connected in parallel with the second inductor. The first inductor and the second inductor are subtractive-polarity coupled. An inductance value of the second inductor is less than an absolute value of mutual inductance generated by coupling of the first inductor and the second inductor.

The present invention includes a method of creating electrical air gap or other low loss low cost RF mechanically and thermally stabilized interdigitated resonate filter in photo definable glass ceramic substrate. A ground plane may be used to adjacent to or below the RF filter in order to prevent parasitic electronic signals, RF signals, differential voltage build up and floating grounds from disrupting and degrading the performance of isolated electronic devices by the fabrication of electrical isolation and ground plane structures on a photo-definable glass substrate.

A high frequency amplification circuit includes transmission amplification circuits 11 and 12; a transmission filter D-Tx whose pass band is a band D of a first frequency band group; transmission filters E-Tx and G-Tx whose pass bands are respectively bands E and G of a second frequency band group; an output matching circuit 31 configured to match the transmission amplification circuit 11 and the transmission filter D-Tx; and an output matching circuit 32 configured to match the transmission amplification circuit 12 and the transmission filters E-Tx and G-Tx. The band D is positioned at a high frequency-side end portion of the first frequency band group, and the band E is positioned at a low frequency-side end portion of the second frequency band group. The output matching circuit 31 includes a low-pass circuit, and the output matching circuit 32 includes an impedance-variable circuit.

A new demodulator with consistent sensibility to signals received from different directions, low power consumption, and low manufacturing cost is provided. The demodulator may include a first demodulator branch and a second demodulator branch electrically connected in parallel, and a DC circuit to provide DC power to the demodulator. The DC circuit has a first diode and a second diode electrically connected in series between a DC power supply Vcc and the ground. The second demodulator branch can share a low pass filter and a DC blocking capacitor of the first demodulator branch for example, and can multiplex or reuse a bias current from the first demodulator branch.