A multimode envelope tracking (ET) circuit and related apparatus is provided. The multimode ET circuit is configured to provide an ET voltage(s) to an amplifier circuit(s) for amplifying a radio frequency (RF) signal(s) that may correspond to a wider range of modulation bandwidth. In this regard, the multimode ET circuit is configured to switch dynamically and opportunistically between different operation modes based on the modulation bandwidth of the RF signal(s). In examples discussed herein, the multimode ET circuit is configured to support a single amplifier circuit in a high-modulation-bandwidth mode and an additional amplifier circuit(s) in a mid-modulation-bandwidth mode and a low-modulation-bandwidth mode. By switching dynamically and opportunistically between different operation modes, it may be possible to reduce undesired series resonance that may cause distortion in the ET voltage(s), thus helping to improve efficiency and performance of the amplifier circuit(s) supported by the multimode ET circuit.

A digital power amplifier comprising two or more individually activatable amplifiers. The outputs of the amplifiers are connected causing an activated amplifier of the two or more amplifiers to load modulate another activated amplifier of the two or more amplifiers.

An envelope tracking system having delay compensation circuitry is disclosed. The envelope tracking system includes transmit circuitry configured to receive an input transmit signal, a gain control signal, and delay compensation values. The envelope tracking system is further configured to generate an envelope tracking signal based on the input transmit signal, the gain control signal, and the delay compensation values, and generate an output transmit signal based on the input transmit signal. The envelope tracking system also includes a power amplifier configured to generate an amplified transmit signal based on the output transmit signal and an operating voltage. The envelope tracking system further includes an envelope tracking integrated circuit configured to control the operating voltage based on the envelope tracking signal. The delay compensation circuitry is configured to generate the delay compensation values based on a peak-to-average ratio of a given modulation type and the gain control signal.

Certain aspects of the present disclosure generally relate to apparatus and techniques for wireless communication. One example apparatus generally includes an antenna terminal, an amplifier, a matching network coupled between the antenna terminal and an output of the amplifier, a first voltage envelope detector coupled to a node between the antenna and the matching network, and a current detection circuit coupled to the amplifier.

An envelope tracking (ET) circuit is provided. The ET circuit includes an amplifier array(s) configured to amplify a radio frequency (RF) signal(s) based on a first input voltage and a second input voltage. The ET circuit includes a pair of tracker circuits each configured to generate a modulated voltage. Control circuitry couples a selected tracker circuit among the tracker circuits to provide a selected modulated voltage (e.g., ET modulated voltage) to the amplifier array(s) as the first input voltage. Depending on usage scenarios, the control circuitry also provides an ET modulated voltage, an average power tracking (APT) modulated voltage, or a constant voltage to the amplifier array(s) as the second input voltage. As such, the ET circuit can support the RF signal(s) modulated in a wide range of modulation bandwidth without compromising efficiency and/or increasing heat dissipation of the amplifier array(s).

An apparatus for providing a supply control signal for a supply unit, the supply unit being configured to provide a variable controlled power supply to the power amplifier. The apparatus includes a determination module configured to determine a deviation of a signal from at least one nominal value; and an adjustment module configured to provide the supply control signal after an adjustment based on the determined deviation.

In an example aspect, an apparatus includes a balanced power amplifier, which performs amplification in the presence of a variable antenna impedance. The balanced power amplifier includes a quadrature output power combiner coupled to a first power amplifying path and a second power amplifying path, detection circuitry, and control circuitry. The detection circuitry includes at least one power detector coupled to an isolated port of the quadrature output power combiner and a resistor coupled between the isolated port and a ground. The at least one power detector is configured to measure power at the isolated port, which is based on a resistance of the resistor. The control circuitry is configured to adjust operating conditions of a first power amplifier of the first power amplifying path and the second power amplifier of the second power amplifying path based on the power that is measured at the isolated port.

Apparatus and methods for envelope tracking systems with automatic mode selection are provided herein. In certain configurations, a power amplifier system includes a power amplifier configured to provide amplification to a radio frequency signal and to receive power from a power amplifier supply voltage, and an envelope tracker including a signal bandwidth detection circuit configured to generate a detected bandwidth signal based on processing an envelope signal corresponding to an envelope of the radio frequency signal. The envelope tracker further includes a switch bank configured to receive a plurality of regulated voltages, a filter configured to filter an output of the switch bank to generate the power amplifier supply voltage, and a mode control circuit configured to control a filtering characteristic of the filter based on the detected bandwidth signal.

The present disclosure is a novel utility of a software defined radio (SDR) based Distributed Antenna System (DAS) that is field reconfigurable and support multi-modulation schemes (modulation-independent), multi-carriers, multi-frequency bands and multi-channels. The present invention enables a high degree of flexibility to manage, control, enhance, facilitate the usage and performance of a distributed wireless network such as Flexible Simulcast, automatic traffic load-balancing, network and radio resource optimization, network calibration, autonomous/assisted commissioning, carrier pooling, automatic frequency selection, frequency carrier placement, traffic monitoring, traffic tagging, pilot beacon, etc. As a result, a DAS in accordance with the present invention can increase the efficiency and traffic capacity of the operators' wireless network.

An automatic gain control system for a receiver for an asymmetrical and/or unbalanced constellation, the system including: an automatic gain control loop adapted to be coupled to both a first transimpedance amplifier coupled to a first analog-to-digital converter forming a first tributary and a second transimpedance amplifier coupled to a second analog-to-digital converter forming a second tributary; wherein the automatic gain control loop is operable for providing an offset gain control voltage to gain balance a transimpedance amplifier voltage and a power associated with the first tributary and a transimpedance amplifier voltage and a power associated with the second tributary. The automatic gain control loop includes an analog automatic gain control loop. The automatic gain control loop is implemented in hardware or firmware.