Systems and methods for controlling a power amplifier includes combining a digital modulated data signal with a digital bias signal to generate a combined digital signal, the digital bias signal generated based on an envelope for the modulated data signal; converting, by a digital-to-analog converter, the combined digital signal into a combined analog signal, the combined analog signal comprising an analog modulated data signal and an analog envelope bias signal; and separating the analog modulated data signal and the analog bias signal onto separate signal paths, wherein the converting is performed using a single digital-to-analog converter.

A high frequency circuit includes: a switch that has terminals, and that switches connection and disconnection between the terminals; a filter that has a first pass band including at least a part of band A and that is connected to one of the terminals; another filter that has a second pass band including at least a part of band B and that is connected to another one of the terminals; and an acoustic wave resonator that has its first end connected to even another of the terminals and its second end connected to the terminal.

Methods and systems are provided for converting wideband signals. In an example system, a wideband signal that includes one or more narrowband signals may be received and handled, with the handling may include selecting a subset of signal processing circuits, from a plurality of signal processing circuits in the system, with the number of selected signal processing circuits being less than the total number of signal processing circuits in the system. Only the selected signal processing circuits are then enabled, such that all remaining signal processing circuits are not enabled. Signal processing adjustment may then be applied, via the subset of signal processing circuits, only to the one or more narrowband signals, such that a remainder of the wideband signal is not adjusted. The handling of the received wideband signal may include separating the one or more narrowband signals from the wideband signal.

A fully integrated power amplifier (PA) employing a transformer combiner with enhanced back-off efficiency includes a first PA to amplify a first radio frequency (RF) signal and a second PA to amplify a second RF signal. A first variable capacitor is coupled between differential output nodes of the first PA. A second variable capacitor is coupled between differential output nodes of the second PA. The differential outputs of the first PA and the second PA are coupled via respective first and second transformers to a load. Capacitance values associated with the first and second variable capacitors are dynamically adjustable based on an amplitude of the RF signal to achieve a desired power efficiency at an output power level.

Systems and methods for controlling a power amplifier includes combining a digital modulated data signal with a digital bias signal to generate a combined digital signal, the digital bias signal generated based on an envelope for the modulated data signal; converting, by a digital-to-analog converter, the combined digital signal into a combined analog signal, the combined analog signal comprising an analog modulated data signal and an analog envelope bias signal; and separating the analog modulated data signal and the analog bias signal onto separate signal paths, wherein the converting is performed using a single digital-to-analog converter.

This automatic gain control circuit is provided with a variable gain amplifier for amplifying a received signal, has a small circuit size, and makes it possible to reduce the effect of superimposed external noise input within the frequency bandwidth of a received signal. The automatic gain control circuit supplies the output of the variable gain amplifier to an analog/digital converter and comprises: a frequency selection circuit that is connected to the output of the analog/digital converter and that selects a signal within the frequency bandwidth of a received signal, said signal having a narrower bandwidth than the frequency bandwidth; and a control signal generation circuit that generates a control signal for the variable gain amplifier on the basis of the strength of the signal selected by the frequency selection circuit.

A discrete time filter, DTF, is described that comprises a summing node; N parallel branches, each branch having a set of input unit sampling capacitances where each unit sampling capacitance is independently selectively coupleable to the summing node; and an output capacitance connected to the summing node. The output capacitance has a value equal to a sum of the sampling capacitances that are to be selectively connected to the summing node; and the discrete time filter further comprises an inductance connected between the summing node and the output capacitance.

An adaptive recursive filter is disclosed. The filter includes a filtering device to iteratively apply a recursive filter to signal frames corresponding to portions of a sampled broadband signal. Each iteration of the recursive filter may include generating an autocorrelation signal of an input signal frame, calculating a ratio of a magnitudes of a pair of successive points of the autocorrelation signal, comparing the ratio to a selected signal detection threshold such that a value of the ratio greater than a threshold indicates at least one signal of interest, calculating an energy-weighted average frequency of the input signal frame as a frequency of interest, comparing a spectral energy of the input signal frame at the frequency of interest to spectral energies of surrounding frequencies to identify a frequency of a narrowband interference signal, and filtering the input signal frame at the identified frequency to remove the identified narrowband interference signal.

A receiving circuit includes a receiver configured to receive a signal, a detector configured to detect arrival of a reception signal based on a signal received by the receiver, a buffer configured to store therein data corresponding to the reception signal, a demodulation processor configured to demodulate data to be supplied, and a controller configured to store the data corresponding to the reception signal in the buffer when the detector does not detect the arrival of the reception signal, and to supply the data stored in the buffer to the demodulation processor when the detector detects the arrival of the reception signal.

Systems and methods are directed to phase modulation of polar coordinates in a transmitter of wireless signals, to achieve high transmit power levels while meeting spectral mask and EVM requirements. An input signal is mapped to a sequence of modulation frequency (e.g., O-QPSK to MSK) to generate a mapped signal. A digital frequency shaping filter is applied to the mapped signal to generate a shaped signal. An adaptive rounding algorithm is applied to the shaped signal to generate a reduced bit-width signal. A digital frequency synthesizer is applied to the reduced bit-width signal to generate an analog waveform for transmission.