Amplifiers inventions 04/06

20060087369 - Amplifier system and method: An amplifier system comprises a first amplifier arranged to receive an input signal and a second amplifier arranged to receive a proportion of the input signal. A first potential divider is arranged to receive the output signal of the second amplifier and to feed a proportion of the output signal...

20060087370 - Charge amplifier: In a charge amplifier, an operational amplifier is provided. The operational amplifier has an inverting input terminal, a non-inverting input terminal, and an output terminal. An adjustable feedback resistor element is provide to be connected between the inverting terminal and the output terminal. A resistance adjusting circuit is provided to...

20060087371 - High efficiency amplifier: An amplifier includes a main amplifier circuit with an input and output. At least one auxiliary amplifier circuit has an input and output, and is selectively operable to operate in combination with the main amplifier circuit. A signal combining network is coupled with outputs of the main amplifier circuit and...

20060087373 - Apparatus and method for controlling bias adaptation bias of a high power amplifier: An apparatus and a method for controlling a bias adaptation bias of a high power amplifier. In the high power amplifier, a coupling operation is performed with respect to an input signal with a predetermined voltage, an amount of attenuation used for attenuating a voltage of the coupled input signal...

20060087372 - Method and apparatus for maintaining constant linearity for a power amplifier over varying load conditions: A circuit and method for applying a dynamically varying collector voltage to a power amplifier is presented. A desired output power is determined, and an input and output power of a power amplifier are measured. A processor determines, for the measured input power and the desired output power, a collector...

20060087374 - Feed forward amplifier employing bias circuit topologies for minimization of rf amplifier memory effects: An RF power amplifier having reduced memory effects is disclosed. This is achieved by a novel design of the DC supply feed network to achieve low impedance across video frequencies, whilst maintaining the correct RF output matching. One or more transmission zeros are provided in the bias circuit transfer function,...

20060087375 - Apparatus and method of controlling bias of power amplifier in mobile communication terminal: Provided is an apparatus for controlling a bias of a power amplifier in a mobile communication terminal, which has the power amplifier for amplifying an input RF signal and an antenna for transmitting the amplified output RF signal. The apparatus includes a power detecting unit for detecting power output from...

20060087376 - Hybrid active combiner and circulator: The hybrid active combiner and circulators serves as a coupler and is a three port network that integrates a directional coupler topology with active devices placed in the coupling paths in order to synthesize a low-loss active combiner circuit or a circulator device with minimal insertion losses. The coupler can...

20060087377 - Amplifier bias circuit, method for biasing an amplifier and integrated circuit comprising an amplifier bias circuit: An amplifier bias circuit connectable to an amplifier device, comprising a first sensor device for sensing a first amplifier characteristic and for providing at a first sensor output a bias signal related to the first amplifier characteristic. The circuit further comprises a second sensor device for sensing a second amplifier...

20060087378 - Preamplifier circuit having a variable feedback resistance: A preamplifier circuit is provided in which the feedback resistance is controllably variable according to the output signal. In particular, when the output is saturated, the resistance is decreased to a smaller value by adding a parallel resistor to the feedback resistance to lower the output to below the saturation,...

20060082413 - Lms-based adaptive pre-distortion for enhanced power amplifier efficiency: Systems and methods are disclosed to adaptively pre-distort a signal prior to being used by a non-linear circuit, such as a higher power amplifier (at transmit) or a low noise amplifier (at receive). The signal is compared with a feedback signal from the non-linear circuit and a metric is calculated...

20060082414 - Method for high efficiency audio amplifier: The present invention introduces methods and circuits to amplify audio signals for driving speakers. An additional feedback circuit is added in an audio amplifier to couple the amplifier stage and output stage of the audio amplifier. The feedback circuit turned off as long as output voltages of the audio amplifier...

20060082415 - Active load with adjustable common-mode level: A differential preamplifier includes an active load with adjustable common-mode output level. The active load includes a transistor pair, a resistor pair, and a current source. The transistor load is employed to provide high gain, low offset, and a large bandwidth for the differential preamplifier. The resistor pair and current...

20060082416 - Method and system for simplifying common mode feedback circuitry in multi-stage operational amplifiers: A method for simplifying common mode feedback circuitry utilized in multi-stage operational amplifiers may comprise generating a first differential output signal by a first amplifying circuit in an amplifying stage and communicating the first differential output signal to a first output of the amplifying stage. A second amplifying circuit in...

20060077003 - Dc offset calibration apparatus: A DC offset calibration device for calibrating a DC offset of an output signal of a gain stage, the DC offset calibration device includes: a digital-to-analog converter (DAC) electrically connected to the gain stage for generating an offset current according to the DC offset of the output signal of the...

20060077004 - Low-distortion differential circuit: A differential feedback system that minimizes even order distortion of a differential circuit. The feedback system includes a feedback circuit for use with a differential circuit to reduce even-order distortion and dc offset of a difference output signal produced by the differential circuit. The feedback circuit includes an integrator coupled...

20060077005 - Current controlled pulse width modulation circuit and class-d amplifier comprising the same: A pulse width modulation (PWM) circuit comprising an input circuit, first and second controllers, and first and second Schmidt triggers. The first controller sets a first voltage level by a first current generated responding to an input signal and an output of the input circuit. The first Schmidt trigger sets...

20060077006 - Delay mismatched feed forward amplifier system using penalties and floors for control: A delay mismatched feed forward amplifier system employing a control system and method using floors and penalties is disclosed. The disclosed control system and method allows the second loop phase adjuster setting to be offset in a repeatable and controlled manner. Applying floors and penalties to offset the steady-state phase...

20060077007 - Three state class d amplifier: A three state class D amplifier (100) comprising a first signal path (1) and a second signal path (1′) substantially identical with the first signal path (1). Each of the signal paths (1, 1′) comprises respective first and second low-pass filter means (10, 10′) coupled to respective input signals (Vn,...

20060077008 - Bipolar rail-to-rail output stage: A bipolar rail-to-rail class-AB output stage that provides improved AC performance in low voltage applications. The bipolar output stage includes an input buffer stage, first and second complementary common emitter stages, and first and second control circuits biased and configured to assure class-AB operation of the first and second common...

20060071709 - Switched-capacitor circuits with reduced finite-gain effect: Operational amplifier circuits (20, 30) including error capacitors (C3, C13) for storing finite gain effect error voltages for correction of output voltages of the circuits (20, 30), are disclosed. The circuits (20, 30) are operated in a sample clock phase to produce an approximation of the output voltage, using negative...

20060071710 - Auto gain controller: A gain-controlled transimpedance amplifier circuit that comprises a first gain unit including an input for receiving a first current and an output, a current source for providing a second current, a second gain unit including an input and an output, a first impedance unit of a first impedance coupled in...

20060071711 - Arbitrary waveform predistortion table generation: Predistortion that will compensate for distortion introduced by a power amplifier circuit is determined by applying a time-varying reference signal to the power amplifier circuit, wherein at each moment the time-varying reference signal has a reference amplitude and a reference phase. A corresponding output signal supplied by the power amplifier...

20060071712 - Variable gain amplifier: A variable gain amplifier is provided. The variable gain amplifier includes a first cascode amplifier which includes a first common source transistor and a first common gate transistor, a second cascode amplifier which forms a differential pair with the first cascode amplifier and includes a second common source transistor and...

20060071713 - Gain control device of transmitter in mobile communication terminal and method thereof: A gain control device of a transmitter in a mobile communication terminal is provided. The device includes a temperature sensor for sensing an external temperature, a power amplifying module for amplifying a radio frequency output, a gain control circuit for controlling a voltage gain of the power amplifying module, a...