A radio frequency circuit includes a switch that includes a terminal connected to an antenna connection terminal and terminals, a duplexer that is connected to the terminal and has a pass band including a communication band A, a duplexer that is connected to the terminal and has a pass band including a communication band B which is available for simultaneous communication with the communication band A, a switch that includes a terminal connected to the terminal and terminals, a duplexer that is connected to the terminal and has a pass band including a communication band C, and a transmit/receive filter that is connected to the terminal and has a pass band including a communication band D.

A radio frequency circuit includes a switch that includes a terminal connected to an antenna connection terminal and terminals, a duplexer that is connected to the terminal and has a pass band including a communication band A, a duplexer that is connected to the terminal and has a pass band including a communication band B which is available for simultaneous communication with the communication band A, a switch that includes a terminal connected to the terminal and terminals, a duplexer that is connected to the terminal and has a pass band including a communication band C, and a transmit/receive filter that is connected to the terminal and has a pass band including a communication band D.

Apparatus and methods for radio frequency (RF) switch control are provided. In certain embodiments, a level shifter for an RF switch includes a first level-shifting n-type transistor, a first cascode n-type transistor in series with the first level-shifting n-type transistor between a negative charge pump voltage and a first output that provides a first switch control signal, a first level-shifting p-type transistor, a first cascode p-type transistor in series with the first level-shifting p-type transistor between a positive charge pump voltage and the first output, and a second cascode p-type transistor between a regulated voltage and a gate of the first level-shifting n-type transistor and controlled by a first switch enable signal.

Apparatus and methods for radio frequency (RF) switch control are provided. In certain embodiments, a level shifter for an RF switch includes a first level-shifting n-type transistor, a first cascode n-type transistor in series with the first level-shifting n-type transistor between a negative charge pump voltage and a first output that provides a first switch control signal, a first level-shifting p-type transistor, a first cascode p-type transistor in series with the first level-shifting p-type transistor between a positive charge pump voltage and the first output, and a second cascode p-type transistor between a regulated voltage and a gate of the first level-shifting n-type transistor and controlled by a first switch enable signal.

Exemplary embodiments are disclosed of current control circuits and methods of modulating supply current from a first device (e.g., a telematics control unit (TCU), etc.) to one or more second devices (e.g., one or more compensators, etc.). In an exemplary embodiment, a method includes modulating a supply current from a first device to a second device into different current values for reporting different information from the second device to the first device. An exemplary embodiment of a current control circuit includes a variable voltage source electrically coupled with a current source and a current sink. The current control circuit is configured to modulate the supply current from a first device to the second device into different current values for reporting different information from the second device to the first device.

An RF transceiver front end includes a receiver limb including a length of transmission line, an impedance matching network, a downstream shunt switch and a downstream further receiver component and a transmitter limb. The impedance matching network is configured to transform the input impedance of the further receiver component to match the input impedance of the receiver limb when the shunt switch is open and the RF transceiver front end is operable in receiver mode. The impedance matching network is further configured to transform the input impedance of the shunt switch to present an open circuit as the input impedance of the receiver limb when the shunt switch is closed and the RF transceiver front end is operable in transmitter mode. The length of transmission line can be from zero to less than λ/4 at the operating frequency of the RF transceiver.

Examples described herein include systems and methods which include wireless devices and systems with examples of mixing input data delayed versions of at least a portion of the respective processing results with coefficient data specific to a processing mode selection. For example, a computing system with processing units may mix the input data delayed versions of respective outputs of various layers of multiplication/accumulation processing units (MAC units) for a transmission in a radio frequency (RF) wireless domain with the coefficient data to generate output data that is representative of the transmission being processed according to a wireless processing mode selection. In another example, such mixing input data with delayed versions of processing results may be to receive and process noisy wireless input data. Examples of systems and methods described herein may facilitate the processing of data for 5G wireless communications in a power-efficient and time-efficient manner.

Examples described herein include systems and methods which include wireless devices and systems with examples of mixing input data delayed versions of at least a portion of the respective processing results with coefficient data specific to a processing mode selection. For example, a computing system with processing units may mix the input data delayed versions of respective outputs of various layers of multiplication/accumulation processing units (MAC units) for a transmission in a radio frequency (RF) wireless domain with the coefficient data to generate output data that is representative of the transmission being processed according to a wireless processing mode selection. In another example, such mixing input data with delayed versions of processing results may be to receive and process noisy wireless input data. Examples of systems and methods described herein may facilitate the processing of data for 5G wireless communications in a power-efficient and time-efficient manner.

The disclosed systems and methods for detecting mirror crosstalk between frequency bands equally above and below the center frequency of a Digital Subcarrier Multiplexing system include: a transmitter configured to insert zero-power symbols on half the frequency bands below center frequency, and insert other zero-power symbols, partially overlapping in time with the first zero-power symbols, on the other half of the frequency bands above center frequency. A receiver zeroes out ASE and other noises during the overlapping portion of all the zero-power symbols, then uses the power detected during the remaining portion of each zero-power symbol in each frequency band to accurately evaluate the mirror crosstalk from the corresponding frequency band on the opposite side of center frequency.

An apparatus for detecting difference in operating characteristics of a main circuit by using a replica circuit is presented. In one exemplary case, a sensed difference in operating characteristics of the two circuits is used to drive a tuning control loop to minimize the sensed difference. In another exemplary case, several replica circuits of the main circuit are used, where each is isolated from one or more operating variables that affect the operating characteristic of the main circuit. Each replica circuit can be used for sensing a different operating characteristic, or, two replica circuits can be combined to sense a same operating characteristic.