An apparatus includes: first and second transistors, each of the first and second transistors includes a gate terminal, a source terminal, and a drain terminal; and a transformer including a primary winding and first and second secondary windings, the primary winding is coupled to a first input node configured to receive an input signal and a second input node configured to receive a potential, the first and second secondary windings are coupled to gate terminals of the first and second transistors and cross-coupled to source terminals of the first and second transistors.

A surface acoustic wave (SAW) filter that receives an aggregate circuit and outputs two or more sub-signals on outputs each of a different frequency band. The sub-signals are amplified by low noise amplifiers and, in one implementation, the amplified sub-signals can be summed. The outputs are connected via a switched passive network so that portions of the sub-signals on the outputs that are not in the selected frequency band are at least partially terminated.

In a semiconductor device, received signals of different frequency bands are input selectively to low noise amplifiers. A plurality of primary inductors are coupled between differential output nodes of the respective low noise amplifiers. A secondary inductor is provided commonly for the primary inductors, and magnetically coupled to the primary inductors. A demodulator converts a received signal transmitted from one of the primary inductors to the secondary inductor by electromagnetic induction, into a signal of a low frequency.

A wireless communication device includes a delay circuit to generate four or more delay signals, an amplifier circuit amplifying the four or more delay signals to generate four or more amplified delay signals, and a combiner circuit combining at least two amplified delay signals to generate an output signal, a second phase of a second amplified delay signal is between a first phase of a first amplified delay signal and a third phase of a third amplified delay signal, gains of the amplifier circuit for the four or more delay signals are controlled such that the output signal is generated by combining the first amplified delay signal and the third amplified delay signal, and a phase of the output signal is between the first phase of the first amplified delay signal and the third phase of the third amplified delay signal.

Digital compensators for use in outphasing-based power amplification systems (e.g., Linear Amplification using Nonlinear Components (LINC) amplifiers and Asymmetric Multilevel Outphasing (AMO) amplifiers) include a short memory nonlinear portion and a long memory linear time invariant (LTI) portion. In various embodiments, compensators are provided that are of relatively low complexity and that are capable of operation at throughputs exceeding a Gigasample per second.

In a class-D amplifier, oscillation phenomenon is suppressed in a high RF range and surge voltage is reduced. An oscillation absorption circuit is connected on the power supply side of the class-D amplifier circuit, and the class-D amplifier circuit and thus connected oscillation absorption circuit equivalently configure an oscillation circuit. Resistance provided in the oscillation absorption circuit is assumed as damping resistance of the oscillation circuit, thereby suppressing the oscillation phenomenon and reducing the surge voltage. The oscillation absorption circuit is made up of the RL parallel circuit of resistance and inductance. The oscillation absorption circuit and the class-D amplifier circuit constitute the oscillation circuit, and the resistance of the oscillation absorption circuit constitutes the damping resistance of the oscillation circuit in the high RF range.

Diversity receiver front end system with impedance matching components. A receiving system can include a controller configured to selectively activate one or more of a plurality of paths between an input of the receiving system and an output of the receiving system. The receiving system can further include a plurality of amplifiers. Each one of the plurality of amplifiers can be disposed along a corresponding one of the plurality of paths and can be configured to amplify a signal received at the amplifier. The receiving system can further include a plurality of impedance matching components. Each one of the plurality of impedance matching components can be disposed along a corresponding one of the plurality of paths and can be configured to reduce at least one of an out-of-band noise figure or an out-of-band gain of the one of the plurality of paths.

Disclosed is a power amplification module which has a comparatively small size and is capable of adjusting the rising characteristic of a gain. The power amplification module includes a first gain control current generation circuit which generates a first gain control current changing with a control voltage, a first bias current generation circuit which generates a first bias current according to the first gain control current, a gain control voltage generation circuit which generates a gain control voltage changing with the control voltage, a first transistor which is emitter-grounded and in which an input signal and the first bias current are supplied to a base thereof, and a second transistor which is cascode-connected to the first transistor and in which the gain control voltage is supplied to a base thereof and a first output signal obtained by amplifying the input signal is output from a collector thereof.

Diversity receiver front end system with amplifier phase compensation. A receiving system can include a first amplifier disposed along a first path, corresponding to a first frequency band, between an input of the receiving system and an output of the receiving system. The receiving system can include a second amplifier disposed along a second path, corresponding to a second frequency band, between the input of the receiving system and the output of the receiving system. The receiving system can include a first phase-shift component disposed along the first path and configured to phase-shift the second frequency band of a signal passing through the first phase-shift component based on a phase-shift caused by the first amplifier at the second frequency band.

An amplifying module having one input terminal and one output terminal and passing an antenna signal input through the input terminal towards the output terminal. The amplifying module includes a first switch connected to the input terminal, a plurality of filters selectable by the first switch, a plurality of amplifiers respectively connected to the plurality of filters and amplifying a signal that has passed through the filters, and a second switch for connecting the amplified signal to the output terminal.