An aspect includes a filtering method including operating a first filter to filter a first input signal to generate a first output signal; operating a second filter to filter a second input signal to generate a second output signal; and merging at least a portion of the second filter with the first filter to filter a third input signal to generate a third output signal. Another aspect includes a filtering method including operating switching devices to configure a filter with a first set of pole(s); filtering a first input signal to generate a first output signal with the filter configured with the first set of pole(s); operating the switching devices to configure the filter with a second set of poles; and filtering a second input signal to generate a second output signal with the filter configured with the second set of poles.

A BAW resonance device comprises a first layer including a cavity located on a first side, a first electrode having a first end located in the cavity and a second end contacting with the first layer, a second layer located on the first side, and a second electrode located on the second layer above the cavity, wherein the first electrode and the second electrode are located on two sides of the second layer. The first electrode comprises a first electrode layer and a second electrode layer, and the second electrode layer and the second layer are located on two sides of the first electrode layer. The second electrode comprises a third electrode layer and a fourth electrode layer, and the second layer and the fourth electrode layer are located on two sides of the third electrode layer. Thus, the electrical resistance is lowered and the electrical losses are 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 high-frequency module includes an antenna terminal, a transmission signal terminal, a reception signal terminal, a plurality of earth terminals, a switch, a transmission filter, a reception filter, and a multilayer board. The multilayer board includes a ground electrode arranged between the transmission filter and the reception filter. The plurality of earth terminals include a first earth terminal and a second earth terminal. When the high-frequency module is viewed in a direction perpendicular to a principal surface of the multilayer board, the reception signal terminal is provided between the antenna terminal and the transmission signal terminal, the first earth terminal is provided between the antenna terminal and the reception signal terminal, and the second earth terminal is provided between the reception signal terminal and the transmission signal terminal.

An amplifier circuit with in-band gain degradation compensation is shown. The amplifier circuit has an input-stage amplifier, at least one intermediate-stage amplifier, and an output-stage amplifier cascaded between an input port and an output port of the amplifier circuit. A compensation capacitor is coupled between the output port of the amplifier circuit and an output port of the input-stage amplifier. A high-order damping circuit is coupled to an output port of the intermediate-stage amplifier.

Bias circuits and methods for silicon-based amplifier architectures that are tolerant of supply and bias voltage variations, bias current variations, and transistor stack height, and compensate for poor output resistance characteristics. Embodiments include power amplifiers and low-noise amplifiers that utilize a cascode reference circuit to bias the final stages of a cascode amplifier under the control of a closed loop bias control circuit. The closed loop bias control circuit ensures that the current in the cascode reference circuit is approximately equal to a selected multiple of a known current value by adjusting the gate bias voltage to the final stage of the cascode amplifier. The final current through the cascode amplifier is a multiple of the current in the cascode reference circuit, based on a device scaling factor representing the relative sizes of the transistor devices in the cascode amplifier and in the cascode reference circuit.

A circuit having an input and an output, the circuit comprising: a first amplifier having a first input, a second input and an output coupled to the output of the circuit; a first capacitor having a first terminal coupled to the first input of the first amplifier and a second terminal coupled to the output of the first amplifier; a first resistor having a first terminal coupled to the first input of the first amplifier and a second terminal; a buffer having an output coupled to the second terminal of the first resistor and an input; a second resistor having a first terminal coupled to the output of the first amplifier and a second terminal coupled to the input of the buffer; a second capacitor coupled between the input of the buffer and ground; and a third resistor coupled between the input of the buffer and the input of the circuit.

A power amplifier circuit amplifies a radio-frequency signal in a transmit frequency band. The power amplifier circuit includes an amplifier, a bias circuit, and an impedance circuit. The amplifier amplifies power of a radio-frequency signal and outputs an amplified signal. The impedance circuit is connected between a signal input terminal of the amplifier and a bias-current output terminal of the bias circuit and has frequency characteristics in which attenuation is obtained in the transmit frequency band. The impedance circuit includes first and second impedance circuits. The first impedance circuit is connected to the signal input terminal. The second impedance circuit is connected between the first impedance circuit and the bias-current output terminal.

An amplification device configured for amplifying a signal with a DC signal component is provided, which comprises a coupling filter circuit having an input terminal and an output terminal. The coupling filter circuit attenuates the DC signal component of an input signal to obtain a filtered output signal. The coupling filter circuit comprises a first capacitor circuit connecting the input terminal to the output terminal; a second capacitor circuit connected in parallel to the first capacitor circuit, a first resistor and a second resistor, wherein the second capacitor, the first resistor and the second resistor are serially connected; and a resistor circuit connected to the input terminal and the output terminal and comprising a third resistor connected to the input terminal and a fourth resistor connected to the output terminal. The amplification device comprises an amplification circuit connected to the output terminal, which amplifies the filtered signal.

A high frequency amplifier circuit includes an input terminal and an output terminal, transmission power amplifiers (11L, 11H) that amplify a high frequency signal in first and second frequency bands, each of which is a part of a communication band, at equal to or higher than a prescribed amplification factor, respectively, switches (21, 31) that exclusively switch connection between the input terminal, the transmission power amplifier (11L), and the output terminal, and connection between the input terminal, the transmission power amplifier (11H), and the output terminal, and a transmission filter that is connected between the output terminal and the switch (31) and has a communication band as a pass band, the first frequency band including a frequency band other than the second frequency band, the second frequency band including a frequency band other than the first frequency band.