Disclosed herein are an apparatus and method for reducing signal distortion. The apparatus for reducing signal distortion includes a signal input unit for receiving Orthogonal Frequency Division Multiplexing (OFDM) signals, a symbol selection unit for selecting an OFDM symbol having a lowest Peak-to-Average-Power-Ratio (PAPR) by applying selective mapping (SLM) to the OFDM signals, an information generation unit for generating side information that includes information about a phase-shift sequence of the selected OFDM symbol, and a signal output unit for outputting a resulting signal by adding the side information to the selected OFDM symbol.

A radio frequency switch system includes a plurality of radio frequency switch circuitries that each include a switch branch coupled between a first branch terminal and a second branch terminal and are configured to allow passage of a radio frequency signal through the switch branch in an on-state and to block the radio frequency signal from passing through the switch branch in an off-state in response to a control signal applied to a branch control terminal of the switch branch. Also included is a switch controller configured to apply the control signal to the branch control terminal of the switch branch of each of the plurality of radio frequency switch circuitries, wherein the control signal has a first voltage level that places the switch branch in the on-state and a second voltage level that places the switch branch in the off-state without digital signal decoding of the control signal.

Radio frequency switch circuitry is disclosed having first and second port terminals, a switch branch having first and second branch terminals, and a branch control terminal, wherein the switch branch is configured to pass an RF signal between the first and second branch terminals in an on-state and block the RF signal from passing between the first and second branch terminals in an off-state in response to a control signal that is coupled with the RF signal and received at the first port terminal. Control signal decoupling circuitry has a control signal input terminal coupled to the first port terminal to receive the control signal coupled to the RF signal and a control signal output terminal coupled to the branch control terminal, wherein the control signal decoupling circuitry is configured to decouple the control signal from the RF signal and provide the control signal to the branch control terminal.

Disclosed is radio frequency switch circuitry that includes a switch branch having a first branch terminal coupled to a first signal port and a second branch terminal coupled to a second signal port, and a branch control terminal, wherein the switch branch has both an on-state and an off-state to control passage of a radio frequency signal between the first signal port and the second signal port in response to a control signal applied to the control terminal. The radio frequency switch circuitry further includes an isolation inductor coupled between the first branch terminal and the second branch terminal such that the isolation inductor is in parallel with the switch branch, wherein the isolation inductor has a given inductance that provides resonance with a total off-state capacitance of the switch branch in the off-state at a center frequency of the radio frequency signal.

A duplex communication system includes a duplexer for transmitting and receiving signals, a transmitter part connected to the duplexer, and a receiver part connected to the duplexer, the receiver part comprising an amplifier for amplifying a received signal to provide an amplified received signal and a demodulator for downconverting the amplified received signal, and a second-order intermodulation distortion (IMD2) compensation module for compensating for second-order intermodulation distortion. The system also includes an adaptive filtering module that obtains a transmitter reference signal, generates filter coefficients for the IMD2compensation module and also adjusts a direct current (DC) bias of the demodulator based on the reference signal.

A FET-based RF switch architecture and method that provides for independent control of FETs within component branches of a switching circuit. With independent control of branch FETs, every RF FET in an inactive branch that is in an open (capacitive) state can be shunted to RF ground and thus mitigate impedance mismatch effects. Providing a sufficiently low impedance to RF ground diminishes such negative effects and reduces the sensitivity of the switch circuit to non-matched impedances.

A MIMO wireless communication device includes, in part, a first transmit path adapted to transmit a first transmit signal from a first antenna, a second transmit path adapted to transmit a second transmit signal from a second antenna, a first receive path adapted to receive a first receive signal, an interference cancellation circuit and a controller. The cancellation circuit includes a cascaded filter structure each filter including a multitude of filter taps each including a variable element. The controller dynamically varies a value applied to each of the plurality of variable elements in accordance with frequency response characteristics of the variable element to remove a portion of a self-interference and/or cross-talk interference signal present in a signal received by the device. The device measures the frequency response characteristic of a multitude of communication channels, used in determining the values, via one or more preamble symbols that are jointly transmitted from the first transmit antenna and the second transmit antenna. A second portion of the interference signal is removed by a digital cancellation circuit using a multitude of samples of a transmitted signal.

According to various example embodiments, an electronic device including: a housing; a conductive member formed as a part of the housing or disposed in the housing as at least a part of the housing; a communication circuit electrically connected to a first region of the conductive member; a ground electrically connected to a second region of the conductive member spaced from the first region of the conductive member; a tunable circuit interposed in an electric connection path electrically connected with the ground in a third region of the conductive member, the third region being located between the first region and the second region of the conductive member; and at least one processor configured to generate a control signal based on a current mode of the electronic device and to provide the control signal to the tunable circuit.

Embodiments disclosed herein relate to reducing insertion loss in a transceiver while improving an operating efficiency of the transceiver. To do so, the transceiver may include isolation circuitry with harmonic distortion rejection circuitry, an electrostatic discharge filter, an out-of-band noise filter, and/or a matching network. In particular, the harmonic distortion rejection circuitry may enable a second harmonic signal to pass from a power amplifier of a transmitter of the transceiver to ground. The electrostatic discharge filter may also provide a path to ground for electrostatic discharge, and the out-of-band noise filter may provide a path to ground for noise signals. The isolation circuitry may substantially remove or decrease interference caused by undesirable signals while reducing a power consumption and thus improving an operating efficiency of the transceiver.

A radio frequency switch circuit with improved harmonic suppression and low insertion loss has an antenna port and a plurality of signal ports. A plurality of transistor switch circuits, are connected to a respective one of the plurality of signal ports and to the antenna port. Each of the transistor switch circuits has a transistor, which in an off state, together with a harmonic suppression capacitor and a parallel inductor both connected thereto, define a tank circuit that suppresses RF signals applied to the corresponding transistor switch circuit from a different one of the transistor switch circuits. The harmonic suppression capacitor is tuned to distribute large signal voltage swings in the RF signal amongst parasitic diodes of the transistor.