A multi-band power amplifier module includes at least one transmission input terminal, at least one power amplifier circuit that receives a first transmission signal and a second transmission signal through the at least one transmission input terminal, a first filter circuit that allows the first transmission signal to pass therethrough, a second filter circuit that allows the second transmission signal to pass therethrough, at least one transmission output terminal through which the first and second transmission signals output from the first and second filter circuits are output, a transmission output switch that outputs each of the first and second transmission signals output from the at least one power amplifier circuit to the first filter circuit or the second filter circuit, and a first tuning circuit that adjusts impedance matching between the at least one power amplifier circuit and the at least one transmission output terminal.

According to one mode of the inventive concept, an amplification device includes a first amplifier configured to amplify an input multi-band signal to a first level, a separating unit configured to separate the multi-band signal having the first level into a first band signal and a second band signal, and a second amplifier configured to amplify the second band signal to a second level.

Radio frequency devices and methods are provided where a network like a filter network or impedance matching network comprises a series connection of at least two inductors.

An audio signal amplification device of the disclosure includes: a delta-sigma modulation part configured to resample an input digital audio signal with a quantization number smaller than a quantization number of the digital audio signal; a pulse-width modulation part configured to convert an output signal from the delta-sigma modulation part into a pulse-width modulation signal which sets a gradation of the output signal in an amplitude direction at a gradation of a pulse width; a power amplification part configured to perform power amplification on an output signal from the pulse-width modulation part; a low-pass filter configured to diminish a component higher than a predetermined cutoff frequency, in an output signal from the power amplification part, and to output the resultant signal; and a correction processing part configured to generate a correction signal for correcting the digital audio signal. The correction processing part includes a switch configured to control coupling of the correction processing part to the low-pass filter. When the switch is on, the correction processing part couples a loudspeaker to the low-pass filter, and generates the correction signal.

A radio-frequency module includes a first inductor and a second inductor disposed on or above a major surface of a module substrate, a resin member, a metal shield layer covering a surface of the resin member, and a metal shield plate disposed on the major surface between the first inductor and the second inductor. The metal shield plate is in contact with a ground electrode of the major surface and the metal shield layer. The first inductor is disposed in any one of a transmitting path, a receiving path, and a transmitting and receiving path. The second inductor is disposed in any one of the transmitting path, the receiving path, and the transmitting and receiving path, other than the path in which the first inductor is disposed.

Example access network devices are described. One example access network device includes a signal processing apparatus. The signal processing apparatus includes a first power amplifier, a second power amplifier, a first filter, a second filter, and a combiner. The first filter filters a second signal obtained by the first power amplifier, to obtain a first sub-signal belonging to a first frequency band and a second sub-signal belonging to a second frequency band. The second filter filters a fourth signal obtained by the second power amplifier, to obtain n sub-signals including at least a third sub-signal belonging to a third frequency band. The combiner combines the first sub-signal and i sub-signals in the n sub-signals based on a preset condition, to obtain a first combined signal. The communication module sends the first combined signal by using a first port, and sends the second sub-signal by using a second port.

A driver interface for a switch-based circuit includes an AC coupling capacitor, a first diode or a first series of diodes, and a second diode or a second series of diodes connected in series with the first diode or first series of diodes but with an opposing polarity. The AC coupling capacitor removes a DC voltage from an input bi-level drive signal that does not have the appropriate high and low drive levels needed to switch a FET in the switch-based circuit between fully ON and fully OFF states. The first diode or first series of diodes and the second diode or second series of diodes clamp the resulting AC-coupled drive signal to produce an output bi-level drive signal having the high and low drive levels needed to switch the FET between fully ON and fully OFF states. The driver interface maintains the high and low drive levels of the output bi-level drive signal irrespective of any changes made to the duty cycle or pulse density of the input bi-level drive signal.

A radio-frequency module includes power amplifiers on a major surface of a module substrate, a transmit filter coupled to an output terminal of the power amplifier to pass a transmit signal in a communication band A, a transmit filter coupled to an output terminal of the power amplifier to pass a transmit signal in a communication band C, a transmit filter coupled to an output terminal of the power amplifier to pass a transmit signal in a communication band E, a resin member covering the major surface, a metal shield layer covering a surface of the resin member, and a metal shield plate on the major surface between the power amplifier and the power amplifier and also between the power amplifier and the power amplifier. The metal shield plate is in contact with a first ground electrode at the major surface and also with the metal shield layer.

A transmitter/receiver apparatus including: a transmitter/receiver terminal; a switching amplifier that includes a low-side switching element connected between a ground terminal and a pulse output terminal and a high-side switching element connected between the pulse output terminal and a power supply terminal and that outputs a pulse signal from the pulse output terminal; a filter that passes therethrough and outputs as a transmitted signal a predetermined frequency component of the pulse signal from a transmitter terminal; and a transmit/receive switch unit that switches the connection status between the transmitter/receiver terminal and the transmitter terminal and also switches the connection status between the transmitter/receiver terminal and a receiver terminal. During receiving, on the basis of the connection status between the transmitter/receiver terminal and the transmitter terminal, the low-side and high-side switching elements are fixed to conductive and non-conductive states, respectively, to non-conductive and conductive states, respectively, or both to non-conductive states.

A cascadable AGC amplifier in a signal distribution system includes a low noise cascadable amplifier having a through path and a cascadable output. The cascadable amplifier is also configured to provide AGC over a predetermined input power range. The cascadable AGC amplifier can be configured to provide gain or attenuation. When the cascadable AGC amplifier is implemented in a signal distribution system, typically as part of a signal distribution device, an input signal can be gain controlled and supplied to multiple signal paths without distortion due to degradation of signal to noise ratio or distortion due to higher order amplifier products. The distributed signal is not significantly degraded by distortion regardless of the number of cascadable AGC amplifiers connected in series or the position of the cascadable AGC amplifier in the signal distribution system.