Abstract: A push-pull amplifier includes a pair of transistors, wherein each of the transistors has a control terminal, a first terminal, and a second terminal. A current that flows between the first terminal and the second terminal is controlled in accordance with signals applied to the control terminal, such that when an amount of current flowing between the first terminal and the second terminal of one of the transistors is within a predetermined range, a high-frequency component of the signals input to the control terminal of one of the transistors is amplified, and when this current is outside the predetermined range, the high frequency component is not amplified.

Abstract: An automatic level control circuit comprises a gain controllable amplifier, a comparing and outputting circuit which compares a level of an output signal from the gain controllable amplifier with a reference level and outputs a result of comparison as a comparison result signal; an output signal restricting circuit which restricts the comparison result signal obtained in a period between one zero crossing point and another zero crossing point of the input signal such that a portion of the comparison result signal obtained within a predetermined output time is output, and an attack detecting and outputting circuit which restricts an output signal from the comparing and outputting circuit to the portion of the comparison output signal obtained within the predetermined time when the comparison result signal is output over the predetermined output time and outputs the restricted comparison result signal as an attack detection output signal.

Abstract: An amplifying circuit with a variable supply voltage and a method thereof are disclosed. The amplifying circuit employs a voltage converter to adjust the supply voltage, thereby upgrading the energy efficiency of the circuit. The circuit also includes a control device, which can generate a control signal for controlling the voltage converter according to an output signal or input signal of the circuit.

Abstract: A current source block and a negative resistance generation block are connected in parallel. The negative resistance generation block generates a negative resistance in response to the minute variations of an output voltage. Thus the output resistance of a current source circuit is given by the combined resistance of the negative resistance and the resistance of a resistor in the current source block connected in parallel. The resistance of the resistor in the current source block and the negative resistance are controlled to be substantially the same to thereby increase the output resistance of the current source circuit. The current source circuit serves to increase an output resistance when viewed from an differential output terminal. As a result, use of this current source circuit realizes a differential amplifier providing a high gain.

Abstract: An automatic gain control apparatus receiving an analog signal and outputting a digital signal includes a variable gain amplifier, an A/D converter, and a feedback circuit. The variable gain amplifier amplifies the analog signal with a gain. The A/D converter converts the amplified analog signal to the digital signal. The feedback circuit includes an amplitude level detector, a range detector, and a gain controller. The amplitude level detector generates a first amplitude level and a second amplitude level in response to the digital signal. The range detector generates an adjustment signal in response to the first amplitude level and the second amplitude level. The gain controller adjusts a gain control level for the variable gain amplifier in response to the adjustment signal.

Abstract: Single port characterization of RF amplifier phase and amplitude transfer functions are developed by measuring the output of the amplifier as it is excited by a predetermined frequency over a series of bias steps. One bias step is chosen as a reference level. Amplitude characterization is obtained from measured magnitude at each step in the test sequence. Phase information is extracted from the same measurements by measuring phase and phase trajectory at a reference level, and subtracting measured phase information at a desired step in the test sequence from an estimation of the reference phase trajectory at that step. Reference measurements may be interspersed with other measurements.

Abstract: In some embodiments, an apparatus includes an amplifier circuit and a bias circuit coupled to the amplifier. The amplifier circuit includes an input port and an output port, an input port circuit element coupled to the input port, an output port circuit element coupled to the output port, and an internal signal path to couple the input port circuit element to the output port circuit element. The output port is coupled to the input port, the bias circuit, and the internal signal path.

Abstract: A variable gain amplifier including a stage. The stage having a set of switchable differential pairs. The stage providing a gain range to a signal and adjusting a gain of the signal. At least one differential pair in each stage is permanently enabled. The variable gain amplifier may include a plurality of cascaded stages including the stage. In addition, the variable gain amplifier may be adjusted through an interleaved thermometer coding method.

Abstract: An amplifier circuit includes a transistor having a control terminal, a first and a second terminal, a signal input terminal coupled to the control terminal of the transistor, as well as a transformer with a primary side and a secondary side, the primary side of which is coupled to the first or second terminal of the transistor. The amplifier circuit further includes a signal output terminal coupled to the secondary side of the transformer. Hereby it is possible to provide an amplifier circuit with a better characteristic as opposed to a conventional amplifier circuit, which is further easy to manufacture.

Abstract: A power amplifier system for high efficiency signal amplification of digitally modulated carrier signal or multi-carrier signals is disclosed. The linearity of the amplifier is improved by providing dynamic load line adjustments through implementation of suitably defined transfer functions employing dynamic control of operational aspects of active devices in the power amplifier.

Abstract: The present invention provides a communication semiconductor integrated circuit device equipped with a high-frequency power amplifier circuit including a gain control amplifier and a bias circuit which supplies such a bias current as to linearly change the gain of the gain control amplifier, and a wireless communication system using the same. A bias current generating circuit which supplies a bias current to a linear amplifier that constitutes the communication high-frequency power amplifier circuit, comprises a plurality of variable current sources respectively different in current value and start level. These variable current sources are controlled according to an input control voltage and thereby combine their currents into a bias current. The combined bias current changes exponentially with respect to the input control voltage.

Abstract: An apparatus reducing non-linearity in an output signal presented at an output locus of an amplifier device having an output unit coupled with the output locus, the output unit having at least one first operating characteristic contributing to the non-linearity, includes a compensating unit coupled with the output locus. The compensating unit has at least one second operating characteristic cooperating with the at least one first operating characteristic to effect the reducing.

Abstract: A differential amplifier that employs mutually coupled inductors to provide desired levels of inductance in a substantially smaller form factor in comparison to individual inductor components. Mutually coupled inductors according to the present teachings may also be used to increase common mode rejection in a differential amplifier.

Abstract: According to one embodiment of the invention, an amplifier includes a gate bias circuit operable to generate a gate bias voltage and a common gate amplifier that includes a transistor having a gate biased by an output of the gate bias circuit and also having a source connected to an inductor for providing a path to ground for direct current flowing through the transistor. According to another embodiment of the invention, a method for amplifying a signal by an amplifier includes generating a gate bias voltage indicative of a difference between a reference voltage and an output voltage of the amplifier, biasing the gate of the common-gate amplifier with the gate bias voltage, and blocking, by a passive device, alternating current signals from flowing from the source of the transistor to ground.

Abstract: Low current differential signal/swing I/O interfaces and techniques can be implemented. An output interface converts input data signals to differential current signals for transmission over transmission lines. When the differential current signals are received by an input interface, they are converted to differential voltage signals and appropriately amplified.

Abstract: An integrated circuit includes a resistive circuit with reduced mismatch that includes a primary resistive network with several main resistances (Rp) each having the same theoretical main value. It also includes an auxiliary resistance (Rau) having an auxiliary theoretical resistive value equal to the product or to the quotient of the theoretical main resistive value by ?{square root over (2)}. All these resistances are connected together so as to attribute a theoretical overall resistive value to the primary resistive network equal to the theoretical auxiliary resistive value.

Abstract: An audio system includes a switch mode amplifier that provides an output signal at an output for driving a load based on at least one control signal. A control system provides the at least one control signal to control the amplifier according to an operating mode of the audio system. In a first mode, the control system providing the at least one control signal to actively control an equivalent output impedance at the output of the amplifier, gradually adjusting the equivalent output impedance from a high-impedance state to a low impedance state, so as to mitigate a voltage drop across the load (e.g., including one or more speakers) when the amplifier is activated to a second mode corresponding to the low impedance state.

Abstract: A device for differential-mode processing of an incident voltage relative to a reference voltage includes a differential circuit including a voltage/current conversion block having a differential input, designed to receive the incident voltage at a first input and the reference voltage at a second input. A current amplification block includes a gain module and a current subtraction module. A current/voltage conversion block includes an operational amplifier with differential transimpedance supplied with a common-mode voltage, receiving the two currents output from the amplification block at its input, and delivering two calibrated opposing voltages at its output that are centered around the common-mode voltage.

Abstract: A unity gain amplifier has a current mirror. A compensation circuit has an input coupled to an output of the current mirror. An output transistor has a base coupled to the output of the current mirror and a source of the output transistor is coupled to an output of the compensation circuit. The compensation circuit has a resistor in series with a capacitor.

Abstract: A low-frequency PWM-modulated signal and a high-frequency, unmodulated signal for generating a high-frequency PWM-modulated signal is employed directly for driving an output stage of a device for noise suppression. The low-frequency signal and the high-frequency signal is advantageously provided by a microcontroller which already has an AD converter on the input side. The microcontroller furthermore already makes a PWM output signal with a high bit width available which has the high resolution necessary for driving the loudspeaker.