A package or a chip including a linear amplifier and a power amplifier is provided, wherein the linear amplifier is configured to receive an envelope tracking signal to generate an amplified envelope tracking signal, the power amplifier is supplied by an envelope tracking supply voltage comprising a DC supply voltage and the amplified envelope tracking signal, and the power amplifier is configured to receive an input signal to generate an output signal.

A transmission circuit includes a power amplifier, a power amplifier forestage circuit and a signal strength adjusting circuit. The power amplifier is configured to amplify an input signal to output an output signal. The power amplifier forestage circuit is configured to output the input signal. The signal strength adjusting circuit includes a conversion circuit, a processing circuit and a storage unit. The conversion circuit is configured to convert the voltage of the output signal into an operation value. The processing circuit is configured to perform an operation according to a target index value stored by the storage unit and the operation value to obtain a differential value. The processing circuit is further configured to adjust the input signal outputted by the power amplifier forestage circuit according to the differential value, so that the power of the output signal is maintained at a target power value.

Systems and method for improving operation of a radio frequency system are provided. One embodiment includes a switching power amplifier that outputs an amplified analog electrical signal based on an input electrical signal and voltage of an envelope voltage supply rail. The switching power amplifier includes a first transistor with a gate that receives the input electrical signal, a source electrically coupled to the envelope voltage supply rail, and a drain electrically coupled to an output of the switching power amplifier; a second transistor with a gate that receives the input electrical signal, a source electrically coupled to ground, and a drain electrically coupled to the output; and a third transistor with a gate that receives the input electrical signal, a drain electrically coupled to the envelope voltage supply rail, and a source electrically coupled to an output of another switching power amplifier.

An apparatus, system, and method are provided for energy conversion. For example, the apparatus can include a trans-impedance node, a reactive element, and a trans-impedance circuit. The reactive element can be configured to transfer energy to the trans-impedance node. The trans-impedance circuit can be configured to receive one or more control signals and to dynamically adjust an impedance of the trans-impedance node. The trans-impedance node, as a result, can operate as an RF power switching supply based on the one or more control signals.

An elastic wave device includes an LiNbO.sub.3 substrate, a first elastic wave resonator including a first IDT electrode and a first dielectric film, and a second elastic wave resonator including a second IDT electrode and a second dielectric film. A Rayleigh wave travels along at least one surface of the elastic wave device. A thickness of the first dielectric film differs from a thickness of the second dielectric film. A propagation direction of an elastic wave in the first elastic wave resonator coincides with a propagation direction of an elastic wave in the second elastic wave resonator. Euler angles of the LiNbO.sub.3 substrate fall within a range of (0°±5°, θ, 0°±10°).

The present invention allows a gain control to be appropriately effected even when a frame including no preamble signal block is used for wireless communications. The following processes are effected in a transmission power control unit 106 of a transmission unit. Specifically, an automatic transmission gain control unit 201 multiplies a transmission signal by a gain value that is the difference between the power of a signal loop-backed from a power amplifier 109 and the power of the transmission signal. A fixed transmission gain multiplying unit 202 multiplies the transmission signal by a predetermined gain value or by the gain value used in the automatic transmission gain control unit 201 during the preceding frame. A selection unit 203 selects the transmission signal as gain-controlled by the automatic transmission gain control unit 201 in a case of a preamble signal block being included in the frame of the transmission signal and selects the transmission signal as gain-controlled by the fixed transmission gain multiplying unit 202 in a case of no preamble signal block being included in the frame of the transmission signal.

Embodiments of this application provide a short-range communications apparatus, a chip, and a control method. The apparatus includes: a gain unit, coupled to an antenna; a first radio frequency RF receive channel, coupled to the gain unit; a first baseband processor, coupled to the first RF receive channel, and configured to receive a first signal from the antenna through the first RF receive channel; a second RF receive channel, coupled to the gain unit; and a second baseband processor, coupled to the second RF receive channel, and configured to receive a second signal from the antenna through the second RF receive channel.

A radio-frequency circuit includes a filter circuit and a power amplifier circuit. The filter circuit includes a first pass band corresponding to a band of a cellular communication system and a second pass band corresponding to a band of a satellite communication system. The power amplifier is connected to the filter circuit. The second pass band is positioned between the first pass band and a third pass band corresponding to a band of a satellite navigation system, or the second pass band at least partially matches the first pass band.

A high frequency circuit includes a main module and a diversity module. The main module includes a duplexer that transmits and receives a signal of a first communication band of a first communication system. The diversity module includes a duplexer that transmits and receives a signal of a second communication band of a second communication system, a reception filter that uses a reception band of the first communication band of the first communication system as a pass band, a power amplifier, a low noise amplifier, and a switch that exclusively switches between connection between a reception filter and the low noise amplifier and connection between the reception filter and the low noise amplifier. The first communication band and the second communication band have the same frequency band.

A radio-frequency module includes a module substrate; a power amplifier; a first switch connected to an input terminal of the power amplifier; a second switch connected to an output terminal of the power amplifier; and a switch control circuit that controls the first switch and the second switch. The first switch, the second switch, and the switch control circuit are included in a semiconductor IC being integrated into a single chip. The power amplifier and the semiconductor IC are mounted on or above the module substrate. When the module substrate is viewed in a plan view, in the semiconductor IC, the switch control circuit is disposed between the first switch and the second switch.