A single servo control loop for amplifier gain control based on signal power change over time or system to system, having an amplifier configured to receive an input signal on an amplifier input and generate an amplified signal on an amplifier output. The differential signal generator processes the amplified signal to generate differential output signals. The single servo control loop processes the differential output signal to generates one or more gain control signals and one or more current sink control signals. A gain control system receives a gain control signal and, responsive thereto, controls a gain of one or more amplifiers. A current sink receives a current sink control signal and, responsive thereto, draws current away from the amplifier input. Changes in input power ranges generate changes in the integration level of the differential signal outputs which are detected by the control loop, and responsive thereto, the control loop dynamically adjusts the control signals.

A signal amplifying circuit and associated methods and apparatuses, the circuit comprising: a signal path extending from an input terminal to an output terminal, a gain controller arranged to control the gain applied along the signal path in response to a control signal; an output stage within the signal path for generating the output signal, the output stage having a gain that is substantially independent of its supply voltage, and a variable voltage power supply comprising a charge pump for providing positive and negative output voltages, the charge pump comprising a network of switches that is operable in a number of different states and a controller for operating the switches in a sequence of the states so as to generate positive and negative output voltages together spanning a voltage approximately equal to the input voltage.

Methods and devices used in mobile receiver front end to support multiple paths and multiple frequency bands are described. The presented devices and methods provide benefits of scalability, frequency band agility, as well as size reduction by using one low noise amplifier per simultaneous outputs. Based on the disclosed teachings, variable gain amplification of multiband signals is also presented.

A semiconductor integrated circuit includes a first transmission power mode configured to transmit by a first power, and a second transmission power mode configured to transmit by a second power smaller than the first power, the semiconductor integrated circuit. The semiconductor integrated circuit includes a first transistor configured to receive and amplify a transmission signal in the second transmission power mode, and an attenuator including a resistor element and a switching element, provided between an output of the first transistor and an output terminal, configured to control attenuation of an output signal of the first transistor.

Distributed amplifier systems and methods are disclosed. An example distributed amplifier system includes first stage traveling wave amplifier (TWA) circuitry that is controllable to provide one of a first set of discrete gain settings. The first stage TWA circuitry includes a first input transmission line, a first output transmission line, and a first plurality of amplifiers coupled antiparallel between the first input transmission line and the first output transmission line. The first set of discrete gain settings has approximately constant logarithmic spacing.

An amplifier according to an embodiment of the present invention includes a first transistor and a second transistor that are connected between a ground point and a power supply. A control terminal of the first transistor is connected to an input terminal. A first terminal of the first transistor is connected to the ground point. A second terminal of the second transistor is connected to an output terminal. The amplifier further includes an impedance element and a variable resistance unit. The impedance element is connected between the second terminal of the second transistor and the power supply. The variable resistance unit is connected between the second terminal of the first transistor and the first terminal of the second transistor.

A LED driving device is provided, which includes a LED string including at least one LED element, at least one channel connected to the at least one LED element, a current regulator configured to regulate a current flowing through the at least one channel according to at least one corresponding control voltage, and a control signal generating circuit configured to generate a control signal based on a difference between a reference voltage and a comparative voltage. The comparative voltage is determined based on a sensing voltage, and the sensing voltage corresponds to an LED current flowing through the LED string. The control signal generating circuit is further configured to generate the at least one corresponding control voltage based on the control signal.

A technology related to a power amplifier used in a wireless communication circuit is disclosed. A radio frequency (RF) power amplifier includes a plurality of unit differential amplifiers of which inputs are connected to a common input terminal and outputs are connected to a common adder, and having a gain of a weight of a corresponding bit of a binary gain control word. Each of the differential amplifiers may be configured as a complementary metal-oxide semiconductor (CMOS) differential cascode amplifier. In addition, the RF power amplifier may include a structure in which a plurality of attenuators of the same structure are cascade-connected so that an attenuation rate may be linearly and digitally controlled and an output of each attenuator is connected to an output adder through differential buffers of which turn-on and turn-off are controlled by a controller.

LNA circuitry includes an input node, and output node, a primary amplifier stage, a first ancillary amplifier stage, and an input gain selection switch. The primary amplifier stage is configured to provide a first gain response between a primary amplifier stage input node and a primary amplifier stage output node, wherein the primary amplifier stage input node is coupled to the input node and the primary amplifier stage output node is coupled to the output node. The first ancillary amplifier stage is configured to provide a second gain response between a first ancillary amplifier stage input node and a first ancillary amplifier stage output node, wherein the first ancillary amplifier stage output node is coupled to the primary amplifier stage output node. The input gain selection switch is coupled between the input node and the first ancillary amplifier stage input node.

Switchable base feed circuit for radio-frequency (RF) power amplifiers. In some embodiments, an RF power amplifier (PA) circuit can include a transistor having a base, a collector, and an emitter, with the transistor being configured to amplify an RF signal. The PA circuit can further include a bias circuit configured to provide a base bias signal to the base of the transistor. The PA circuit can further include a switchable base feed circuit implemented between the bias circuit and the base of the transistor. The switchable base feed circuit can be configured to provide a plurality of different resistance values for the base bias signal between the bias circuit and the base of the transistor. Such a PA circuit can be implemented in products such as a die, a module, and a wireless device.