In a high-frequency module, a plurality of filters are connected to a first switch. A plurality of amplifiers are connected to a second switch. A first inductor is disposed on a common path between a second common terminal of the second switch and a first common terminal of the first switch. A plurality of second inductors are disposed, on a one-to-one correspondence, in sections different from the common path, the sections being included in the plurality of respective signal paths. The first inductor is a surface mount inductor located on a first main surface of a mounting substrate. The plurality of second inductors are each an inductor disposed within an IC chip including the plurality of amplifiers or an inductor including a conductive pattern formed in or on the mounting substrate.

A circuital system that includes a differential low-pass filter having a differential output and operable in a first voltage domain. Some embodiments include a differential integrator including a differential input and a differential output, and operable in a second voltage domain different from the first voltage domain. Some embodiments include a pair of AC coupling capacitors coupling the differential output of the differential low-pass filter to the differential input of the differential integrator.

Audio amplifier circuit includes a pulse width modulation circuit, an auxiliary loop circuit corresponding to a first variable resistance value and a first variable current value, and a main loop circuit corresponding to a second variable resistance value and a second variable current value. Main loop circuit is coupled between a second node, an output terminal, and a first node. Under a condition that auxiliary loop circuit and main loop circuit are turned on, second variable resistance value is decreased and second variable current value is increased after auxiliary loop circuit enters into a first control state, such that main loop circuit enters into a second control state. First variable resistance value is increased and first variable current value is decreased after main loop circuit enters into second control state, such that auxiliary loop circuit is out of first control state.

A wide band matching network for power amplifier impedance matching, the wide band matching network comprising: a power amplifier transistor connected to an output network; the output network including: a series capacitor; an on-chip transformer connected to the capacitor in series, wherein the transformer and the capacitor act as a second order filter; and a port connected to the capacitor and a receiver switch.

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.

Provided herein are amplifiers, such as buffers, with increased headroom. An amplifier stage includes a follower transistor and current source configured to receive a power supply voltage comprising an alternating current component and a direct current component. The alternating current component of the power supply voltage has substantially the same frequency and magnitude as the input signal received by the follower transistor. In radio frequency (RF) and intermediate frequency (IF) buffer applications, for example, the increased headroom can allow for linear buffering of an input signals with increased amplitude so that the output power one decibel (OP1dB) compression point can be increased.

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.

An audio signal modulation and amplification circuit includes a common-mode electric potential controller, a carrier generator, and channel circuits. The common-mode electric potential controller is configured to generate one or more first common-mode electric potentials and second common-mode electric potentials. The carrier generator is adapted to receive the first common-mode electric potential to generate a carrier signal. Each of the channel circuits includes a filter, a comparison circuit, and a driving circuit. The filter is adapted to filter an input signal and generate a filtered signal based on a corresponding one of the second common-mode electric potentials. The comparison circuit is configured to compare the potential of the carrier signal with the potential of the filtered signal to generate a pulse-width modulation signal. The driving circuit is configured to be turned on or off in response to the pulse-width modulation signal to output a load driving signal.

An electronic device is provided. The electronic device includes a first antenna, a second antenna, a transmission/reception path unit, a first reception path unit, a second reception path unit including a low noise amplifier (LNA), a signal path selection unit configured to connect each of the first antenna and the second antenna to the transmission/reception path unit, the first reception path unit, or the second reception path unit, and a radio frequency integrated circuit (RFIC) module or a processor including the RFIC module configured to control the signal path selection unit to have a first state in which the first antenna is connected to the transmission/reception path unit and the second antenna is connected to the second reception path unit or control the signal path selection unit to have a second state in which the first antenna is connected to the first reception path unit and the second antenna is connected to the transmission/reception path unit.

Apparatus and methods for power amplifier bias modulation for low bandwidth envelope tracking are provided herein. In certain embodiments, a power amplifier system for a mobile device includes a power amplifier that amplifies an RF signal and a low bandwidth envelope tracker that generates a power amplifier supply voltage for the power amplifier based on an envelope of the RF signal. The envelope tracking system further includes a bias modulation circuit that modulates a bias signal of the power amplifier based on a voltage level of the power amplifier supply voltage.