An envelope tracking system includes an envelope signal generator, a supply modulator coupled to the envelope signal generator, the supply modulator comprising a switching regulator path configured to provide an output voltage at an output node to a power amplifier when in an average power tracking (APT) mode, the switching regulator path configured to operate together with a linear path to provide the output voltage at the output node to the power amplifier when in an envelope tracking (ET) mode, a capacitor having a first and second terminal, the first terminal coupled to ground, a switch coupled between the output node and the second terminal of the capacitor, the switch being configured to selectively disconnect the capacitor from the output node, and a circuit coupled between the output node and the second terminal of the capacitor, the circuit comprising a bi-directional current-limiting switch, the circuit configured to charge or discharge the capacitor such that a voltage across the capacitor changes from a first voltage to a second voltage.

A transmitter circuit is disclosed. The transmitter circuit includes a frequency circuit configured to generate a frequency signal, a power amplifier configured to drive an antenna with a drive signal according to the frequency signal, and a programmable delay circuit configured to controllably extend a propagation delay between the frequency signal generated by the frequency circuit and the drive signal of the power amplifier. The programmable delay circuit is programmed with a programming value which causes the transmitter circuit to pass a calibration test.

A system for linearized-mixer interference mitigation includes first and second linearized frequency downconverters; a sampling analog interference filtering system that, in order to remove interference in the transmit band, filters the sampled BB transmit signal to generate a cleaned BB transmit signal; an analog interference canceller that transforms the cleaned BB transmit signal to a BB interference cancellation signal; and a first signal coupler that combines the BB interference cancellation signal and the BB receive signal in order to remove a first portion of receive-band interference.

A pair of programmable state machines may be included in a transmitter integrated circuit of a scanner (e.g. a body scanner) to control the sub-circuits of the transmitter integrated circuit. The first programmable state machine may be used to control the signal processor of the transmitter that facilitates generation of a signal to be transmitted at a target, such as a user to be scanned. The second programmable state machine may be used to control the transmitter's selection of a transmission channel for transmitting the signal in which provides the signal to be transmitted to an antenna. Further, the receiver integrated circuit of the scanner may include a similar pair of programmable state machines for controlling the receive signal processor and receiver of the receiver integrated circuit. The inclusion of the state machines can reduce both the scan time and the circuit complexity of the scanner.

A transmitter having: an oscillator to generate a clock signal and synthesize frequencies for modulating a message to generate first signals to a first direct current power line, and a control circuit to adjust timing of the first signals in synchronization with second signals transmitted in a second direct current power line disposed in a vicinity of the first direct current power line, by synchronizing phase of the first and second signals or by transmitting the first and the second signals in separate time windows.

An integrated circuit is disclosed. The integrated circuit includes a set of transceivers comprising a plurality of transceivers, all configured to transmit in the same transmit frequency band and receive in the same receive frequency band. Furthermore, the integrated circuit has a set of frequency synthesizers including a separate frequency synthesizer associated with each transceiver in the set of transceivers, wherein each frequency synthesizer in the set is configured to generate a local-oscillator (LO) signal to its associated transceiver. Moreover, the integrated circuit includes a control circuit configured to control the set of frequency synthesizers such that nearest neighbors in the set of frequency synthesizers generate LO signals at different frequencies (f.sub.1, f.sub.2, f.sub.3, f.sub.4).

Methods, systems, and devices for channelizing a wideband waveform for transmission on a spectral band comprising unavailable channel segments are described. Generally, the described techniques provide for transmitting and receiving wideband waveforms when channels of a system bandwidth are unavailable for transmission. A transmitter may separate a first wideband signal into segments, with each segment a bandwidth corresponding to a channel of the system bandwidth, and may map the segments to the available channels. The transmitter may combine the mapped segments into a second wideband waveform and transmit the second wideband waveform using the available channels. A receiver may receive a first wideband signal waveform and may separate the first wideband signal waveform into segments, de-map the segments and combine the de-mapped segments into a second wideband waveform for demodulation. The techniques may be used to transmit and receive wideband waveforms over tactical data links.

A system for linearized-mixer interference mitigation includes first and second linearized frequency downconverters; a sampling analog interference filtering system that, in order to remove interference in the transmit band, filters the sampled BB transmit signal to generate a cleaned BB transmit signal; an analog interference canceller that transforms the cleaned BB transmit signal to a BB interference cancellation signal; and a first signal coupler that combines the BB interference cancellation signal and the BB receive signal in order to remove a first portion of receive-band interference.

Apparatuses and methods are disclosed regarding a multiband transmitter. In an example aspect, an apparatus for processing signals for wireless transmission includes a wireless interface device. The wireless interface device includes an upconverter, a tunable filter, and a driver amplifier. The upconverter has an output and is configured to upconvert a baseband frequency to a radio frequency based on a local oscillator signal. The tunable filter has an input and an output; the input of the tunable filter is coupled to the output of the upconverter. The driver amplifier has an input; the input of the driver amplifier is coupled to the output of the tunable filter.

A radio frequency circuit includes an amplifier capable of amplifying a first radio frequency signal and a second radio frequency signal that has a frequency different from a frequency of the first radio frequency signal. Here, the amplifier uses a first power-supply voltage to amplify one of the first radio frequency signal and the second radio frequency signal and uses a second power-supply voltage to amplify both the first radio frequency signal and the second radio frequency signal together. A value of the second power-supply voltage is greater than a value of the first power-supply voltage.