An amplifying device includes a first amplifier, a voltage-limiting circuit, a second amplifier, a first controller, and a second controller. The first amplifier is configured to amplify an input signal. The voltage-limiting circuit is configured to limit a voltage of an output signal from the first amplifier to within a limit range. The second amplifier is configured to amplify an output signal from the voltage-limiting circuit. The first controller is configured to control the limit range in accordance with a current supplied to a load from the second amplifier. The second controller is configured to decrease an amplification factor of the first amplifier in a state in which the voltage-limiting circuit limits the voltage of the output signal from the first amplifier.

An audio signal processor includes a difference detecting circuit, a gain switching circuit, a differential gain value changing circuit, and a gain control circuit. The difference detecting circuit detects a differential gain value being a first total gain value being a gain value to be switched and a second total gain value being the gain value that has been switched. The gain switching circuit switches the first total gain value to the second total gain value. The differential gain value changing circuit decreases the differential gain value as time passes. The gain control circuit corrects an inputted signal with the differential gain value that decreases as time passes.

A method comprises: measuring reflected and forward power at a power amplifier output; determining if the reflected power equals to or exceeds a first level; if the reflected power is equal to or exceeds the first level, then reduce power of a power amplifier input signal; determining if a standing wave ratio at the power amplifier output equals or exceeds a second level; if the standing wave ratio at the power amplifier output equals or exceeds the second level, then reducing the power amplifier input signal power level and/or sending an alarm; determining if the power amplifier output power equals or exceeds a third level; and if the power output from the power amplifier equals or exceeds the third level, then reducing the power amplifier input signal power level until such power level is less than or equal to the third level and/or sending an alarm.

An output power control device includes: an attenuator to attenuate power of a high-frequency signal output from an oscillator; a high-frequency power amplifier to amplify the power of the high-frequency signal output from the attenuator; a monitor circuit to monitor the power of the high-frequency signal output from the high-frequency power amplifier; and a controller to control an attenuation amount of the attenuator based on the monitor signal output from the monitor circuit or based on attenuation amount setting data from a data unit. The oscillator generates the high-frequency signal in synchronization with a trigger signal. The controller starts control of the attenuation amount of the attenuator based on the attenuation amount setting data, in synchronization with the trigger signal, and, after receiving the monitor signal, the controller controls the attenuation amount of the attenuator based on the monitor signal.

The present disclosure relates to a power amplifier (PA) system provided in a semiconductor device and having feed forward gain control. The PA system comprises a transmit path and control circuitry. The transmit path is configured to amplify an input radio frequency (RF) signal and comprises a first tank circuit and a PA stage. The control circuitry is configured to detect a power level associated with the input RF signal and control a first bias signal provided to the PA stage based on a first function of the power level and control a quality factor (Q) of the first tank circuit based on a second function of the power level.

Approaches for compensating for RF imperfections in a system that comprises two or more independent modules. The two or more independent modules may be comprised within a remote PHY node (RPN). RF calibration data is stored in one or more non-volatile mediums for two or more independent modules. Each of the two or more independent modules are electronically coupled in a sequence via a transmission medium. A first independent module digital compensates a RF signal for a set of two or more modules that are coupled together in sequence via the transmission medium. The first independent module may correspond to a remote PHY device (RPD).

Provided is a power amplification circuit that includes: a first transistor that has an emitter to which a first radio frequency signal is supplied, a base to which a first DC control current or DC control voltage is supplied and a collector that outputs a first output signal that corresponds to the first radio frequency signal; a first amplifier that amplifies the first output signal and outputs a first amplified signal; and a first control circuit that supplies the first DC control current or DC control voltage to the base of the first transistor in order to control output of the first output signal.

According to one mode of the inventive concept, an amplification device includes a first amplification unit configured to amplify an input signal when a power level of the input signal is within a first range, a second amplification unit configured to amplify the input signal when the power level of the input signal is within a second range, and an abnormality sensing unit configured to sense an occurrence of an abnormality in the second amplification unit. The abnormality sensing unit senses reverse power regarding an output of the second amplification unit to generate a sensed voltage and compares the sensed voltage with a reference voltage to sense whether an abnormality occurs in the second amplification unit.

Described herein are variable gain amplifiers and multiplexers that embed programmable attenuators into switchable paths to provide variable gain for individual amplifier inputs. The variable gain for an individual input is provided using a amplification stage that is common for each input of the amplifier. A variable attenuation is provided for individual inputs through a combination of a band selection switch and an attenuation selection branch. The attenuation can be tailored for individual inputs and can depend on a gain mode of the amplifier.

A low noise amplifier for an RF sampling analog front end. The amplifier includes digital step attenuation for applying a selected attenuation to signals received at an input node, and a gain stage coupled to amplify the attenuated signal from the digital step attenuation circuit. In a differential amplifier implementation, a first input capacitor is coupled between a positive side input node and an output of the negative side digital attenuation circuit, and a second input capacitor is coupled between a negative side input node and an output of the positive side digital step attenuation circuit. In some embodiments, variable feedback circuits are coupled between each input node and an output of the corresponding gain stage, to selectively apply active termination at the input at high gain settings of the amplifier. Variable input and output resistors, and programmable noise filtering at the output, are provided in some embodiments.