Envelope tracking power amplifiers with advanced gain shaping are provided. In certain implementations, a power amplifier system includes a power amplifier that amplifies a radio frequency (RF) signal and an envelope tracker that controls a voltage level of a supply voltage of the power amplifier based on an envelope of the RF signal. The power amplifier system further includes a gain shaping circuit that generates a gain shaping current that changes with the voltage level of the supply voltage from the envelope tracker. For example, the gain shaping circuit can include an analog look-up table (LUT) mapping a particular voltage level of the supply voltage to a particular current level of gain shaping current. Additionally, the gain shaping circuit biases the power amplifier based on the gain shaping current.

A method for receiving data includes receiving a transmission signal through a channel, adjusting the intensity of the transmission signal to generate an adjusted transmission signal according to an analog gain level, converting the adjusted transmission signal into a digital signal, filtering the digital signal to generate a filtered signal according to a set of filter coefficients, and adjusting intensity of the filtered signal according to a digital gain level. The method further includes, in a training mode, estimating a transmission condition of the channel and adjusting the analog gain level and the digital gain level according to the transmission condition for obtaining convergent values for the set of filter coefficients before the training mode ends, and in a data mode, performing a gain adjustment operation to adjust the analog gain level and to adjust the digital gain level according to the adjustment made to the analog gain level.

According to one aspect, embodiments of the invention provide an amplifier system comprising a first phase shifter configured to generate, based on an input signal, a first signal and a second signal, the second signal being out of phase with the first signal, a first amplifier configured to apply a first gain to the first signal to produce a gain adjusted first signal, a second amplifier configured to apply a second gain to the second signal to produce a gain adjusted second signal, a second phase shifter configured to combine the gain adjusted first and second signals to produce an output signal, and a controller configured to identify a high voltage swing across the first amplifier and, in response to identifying the high voltage swing, adjust the first gain to reduce output power of the first amplifier and adjust the second gain to increase output power of the second amplifier.

Various aspects of the present disclosure generally relate to wireless communication. In some aspects, a receiver device may identify an analog to digital converter (ADC) clipping rate for one or more measurement windows. The receiver device may modify, based at least in part on a determination that the ADC clipping rate does not satisfy a threshold, a low noise amplifier (LNA) gain value to be used by the receiver device. The receiver device may receive a signal using the modified LNA gain value. Numerous other aspects are provided.

An interrogation device, for locating a wireless device, includes a receiver and digital processing circuitry. The receiver includes one or more receiver stages having adjustable gains, and is configured to receive from the wireless device a signal that carries a packet including a direction-finding field, wherein, during reception of the direction-finding field, multiple different temporal sections of the received signal traverse different wireless channels due to switching among different antennas in the interrogation device or in the wireless device and thus have multiple different received-signal levels. The digital processing circuitry is configured, based on the multiple received temporal sections of the signal during reception of the direction-finding field, to (i) adapt the adjustable gains of the receiver stages and (ii) estimate a position of the wireless device.

Techniques for controlling the output of a power amplifier are disclosed. In one embodiment, the techniques may be realized as a system that includes a power amplifier and a controller coupled to the power amplifier to form a feedback loop. The power amplifier is enabled or disabled in response to a blanking signal. The controller includes an accumulator that stores an accumulated error of the feedback loop. The controller suspends operation of the accumulator when (1) a level of the input signal is below a first threshold for an amount of time that exceeds a second threshold, (2) the blanking signal indicates that the power amplifier is disabled, or (3) both. The controller resumes operation of the accumulator when (1) the level of the input signal is above the first threshold and (2) the blanking signal indicates that the power amplifier is enabled.

A bidirectional RF circuit, preferably including a plurality of terminals, a switch, a transistor, a coupler, and a feedback network. The circuit can optionally include a drain matching network, an input matching network, and/or one or more tuning inputs. In some variations, the circuit can optionally include one or more impedance networks, such as an impedance network used in place of the feedback network; in some such variations, the circuit may not include a coupler, switch, and/or input matching network. A method for circuit operation, preferably including operating in an amplifier mode, operating in a rectifier mode, and/or transitioning between operation modes.

Quadrature error correction (QEC) for radio transceivers are provided herein. In certain embodiments, a transceiver includes an in-phase (I) signal path including a first controllable amplifier coupled to a first data converter, and a quadrature-phase (Q) signal path including a second controllable amplifier coupled to a second data converter. The transceiver further includes a QEC circuit operable to correct for a quadrature error between the I signal path and the Q signal path by adjusting a gain of the first controllable amplifier and/or a gain of the second controllable amplifier.

An apparatus including an electronic circuit. The apparatus includes a path unit configured to form a first impedance for controlling a gain of an input signal. The apparatus also includes a shunt unit configured to form a second impedance for performing attenuation between the path unit and a ground, wherein the path unit forms the first impedance using an on-resistance of at least one transistor.

Processes and systems for producing glass fibers having regions devoid of glass using submerged combustion melters, including feeding a vitrifiable feed material into a feed inlet of a melting zone of a melter vessel, and heating the vitrifiable material with at least one burner directing combustion products of an oxidant and a first fuel into the melting zone under a level of the molten material in the zone. One or more of the burners is configured to impart heat and turbulence to the molten material, producing a turbulent molten material comprising a plurality of bubbles suspended in the molten material, the bubbles comprising at least some of the combustion products, and optionally other gas species introduced by the burners. The molten material and bubbles are drawn through a bushing fluidly connected to a forehearth to produce a glass fiber comprising a plurality of interior regions substantially devoid of glass.