A power amplifier module including an input configured to receive an input radio frequency signal, the input radio-frequency signal including a series of data symbols, an output configured to provide an output radio-frequency signal, a power amplifier having a signal input to receive the input radio-frequency signal and a power supply input to receive a supply voltage, the power amplifier configured to amplify the input radio-frequency signal to provide the output radio-frequency signal, and a controller to receive an indication of a peak output power level of an upcoming data symbol in the series of data symbols, to adjust at least the supply voltage provided to the power amplifier based on the peak output power level of the upcoming data symbol, and to configure the power amplifier module to maintain a substantially constant gain over the series of data symbols.

A display apparatus and a method for processing audio are provided, the display apparatus includes a circuit board provided with a hybrid circuit, a filter circuit and a speaker; the hybrid circuit is configured to receive an original audio signal and superpose a first sub-signal of the original audio signal on a second sub-signal of the original audio signal to obtain a hybrid audio signal; the first sub-signal includes at least one channel of audio signal, the second sub-signal includes at least two channels of audio signal; the filter circuit is configured to filter the hybrid audio signal according to a frequency characteristic of the first sub-signal and the second sub-signal to obtain a restored original audio signal; and the speaker, connected with the filter circuit, is configured to output the restored original audio signal.

An amplifying apparatus includes a variable gain amplifying circuit configured to operate in a gain mode selected from a plurality of gain modes in response to a first control signal during operation in an amplification mode, a variable attenuation circuit configured to have an attenuation value that is adjusted in response to a second control signal, and a phase compensation value which compensates for a phase distortion in the selected gain mode, and a control circuit configured to control the selecting of the gain mode, the adjusting of the attenuation value and the phase compensation value, based on the first and second control signals.

A variable RF attenuator includes a substrate, a first microstrip trace, a first thin film resistor, a second microstrip trace, and a wire bond. The substrate includes a dielectric layer. The first thin film resistor is disposed on the substrate. The first microstrip trace is disposed on the substrate and the first thin film resistor. The second microstrip trace is disposed on the substrate and is uncoupled from the first microstrip trace. The wire bond extends from the second microstrip trace to a position on the first microstrip trace. The position is selected to tune RF attenuation over a conductive path defined by the first microstrip trace, the wire bond, and the second microstrip trace.

A radio frequency signal transmission circuit includes a direct current blocking unit, a biasing impedance circuit, and a radio frequency element. The direct current blocking unit has a first terminal for receiving an input signal, and a second terminal coupled to a first bias voltage terminal. The biasing impedance circuit has a first terminal coupled to the first bias voltage terminal for providing a first bias voltage, and a second terminal coupled to a second bias voltage terminal for receiving a second bias voltage. The radio frequency element is coupled to the first bias voltage terminal, and receives and processes the input signal. When the biasing impedance circuit operates in a first mode, the biasing impedance circuit provides a first impedance. When the biasing impedance circuit operates in a second mode, the biasing impedance circuit provides a second impedance greater than the first impedance.

An inductor includes a substrate, and a first coil pattern disposed on one surface of the substrate and having a spiral shape comprising a plurality of turns, wherein as the first coil pattern extends inwardly towards a center of the first coil pattern, a pattern width of the first coil pattern decreases while a center-to-center distance between two adjacent turns of the first coil pattern increases.

A transmission unit includes a first transistor that amplifies power of a first signal and outputs a second signal, a power supply circuit that supplies to the first transistor a power supply voltage that changes in accordance with an amplitude level of the first signal, and an attenuator that attenuates the first signal in such a manner that an amount of attenuation of the first signal increases with a decrease in the power supply voltage when the power supply voltage is less than a first level.

A power amplifier circuit includes a first transistor amplifying a first signal; a second transistor amplifying a second signal; a bias circuit supplying a bias current or voltage to a base or gate of the second transistor; and an attenuator attenuating the first or second signal in accordance with a control voltage supplied from the bias circuit. The attenuator includes a first diode to which the control voltage is supplied, a third transistor including a collector connected to a supply path of the first or second signal, an emitter connected to a ground, and a base to which the control voltage is supplied from the first diode, and a capacitor connected in parallel with the first diode. The control voltage decreases as a second signal power level increases. The third transistor allows part of the first or second signal to pass to the emitter in accordance with the control voltage.

An amplification circuit includes: an amplifier including a transistor that is connected between an input terminal and an output terminal; an input matching network that is connected between the input terminal and an input side of the amplifier and converts an impedance from a low impedance to a high impedance; a limiter circuit that is connected between a node between the input matching network and the input side of the amplifier, and ground and includes two diodes connected in opposite directions to each other; and a capacitor that is connected in series with the limiter circuit between the node and ground.

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.