Amplifiers inventions 03/06

20060066394 - Characterizing linearity of amplifiers: The present invention provides a method and an apparatus for assessing a capability, for example, linearity of an amplifier, such as that of a power amplifier including a radio frequency amplifier. In one embodiment, the method comprises defining a first figure of merit for a power amplifier based on a...

20060066395 - Variable gain amplifier with direct current offset correction: Techniques to provide DC-offset correction in a variable gain amplifier are described....

20060066396 - Circuit for power amplification: A radio frequency (RF) power amplifier, including an external control loop and a protection circuit, which functions to maintain a constant output power during variations in impedance on the RF load. In the external control loop a collector current from an output transistor is detected and then regulated with respect...

20060066398 - High frequency power amplifier circuit and electric component for high frequency power amplifier: In a high frequency power amplifier circuit in which bias voltages are applied to the transistors for amplification by current mirroring, this invention enables preventing waveform distortion near the peak output power level by allowing sufficient idle currents to flow through the transistors for amplification, while enhancing the power efficiency...

20060066397 - Multi-stage variable gain amplifier utilizing overlapping gain curves to compensate for log-linear errors: A multi-stage variable gain amplifier is disclosed that utilizes overlapping gain curves to compensate for log-linear errors. Each gain stage is configured to approximate a log-linear response with a sinusoidal error term such that a portion of the curve has positive errors and a portion of the curve has negative...

20060066399 - Amplifier arrangement having an adjustable gain, and use thereof: According to one or more aspects of the present invention, an amplifier arrangement is disclosed. The arrangement comprises a first, a second and a third amplifier. The first and second amplifiers are coupled to one another such that they form a negative feedback loop. In addition, an output node of...

20060066400 - Differential amplifier with cascode control: A differential amplifier includes an input stage, an output stage, and a control unit. The input stage generates differential currents in response to a voltage difference between differential input signals. The output stage generates an output signal at an output node. The control unit is coupled between the input stage...

20060066401 - Method for setting an amplifier, and corresponding amplifier circuit: An amplifier and method of setting the amplifier is presented. The amplifier is set by setting a mean value between voltage values at first and second outputs of the amplifier. The mean value is pulled towards a certain voltage potential. A circuit node is coupled to the first and to...

20060066402 - Amplifier circuit and input circuit: A disclosed amplifier circuit is capable of changing a gain to amplify an input signal according to a control signal. The amplifier circuit comprises a differential amplifier circuit adapted to receive and amplify the input signal to output the amplified input signal as an output signal, a first resistance and...

20060066403 - Power amplifier and method for power amplification: The invention provides a method for reducing power dissipation in a power amplifier used in wireless communication systems, said power amplifier having transistors showing a quiescent current, wherein the quiescent current of the power amplifier is adaptively changed according to the average output power of the power amplifier. A power...

20060066404 - Semiconductor integrated circuit for high frequency power amplifier and electric components with the semiconductor integrated circuit: In a high frequency power amplifier circuit in which bias voltages are applied to the transistors for amplification by current mirroring, The power amplifier includes a detection circuit including a transistor for detection which receives the AC component of an input signal to the last-stage transistor for amplification at its...

20060066406 - High frequency power amplifier: The invention provides a wide-band, low-noise, and small-sized high frequency power amplifier that has small temperature dependence of the gain and is excellent in input matching. A parallel circuit consisting of a resistor whose resistance depends strongly on temperature and a conventional resistor is inserted serially into a signal path...

20060066405 - Robust monolithic automatic bias circuit with current setting apparatus: A bias circuit includes a regulator circuit an d a current diverting circuit. The regulator circuit includes a load resistor, a first transistor, and feedback control circuitry for biasing the first transistor such that a nominal quiescent current flows through the first resistor and first transistor. A current diverting circuit...

20060066407 - Amplification gain stages having replica stages for dc bias control: An amplification apparatus is provided that includes a plurality of gain stages including a first gain stage having first and second transistors and a second gain stage having third and fourth transistors. A plurality of replica stages may also be provided that includes a first replica stage and a second...

20060066408 - Base current compensation circuit for a bipolar junction transistor: A method and apparatus for compensating a base current of a bipolar junction transistor by replicating operating conditions of the BJT in a compensating circuit. An output current of the compensating circuit is fractionally related to the base current and thus can be supplied to an operational circuit comprising the...

20060066409 - Integrated direct drive inductor means enabled headphone amplifier: A headphone driver amplifier operative from a single DC voltage supply, coupled directly to the headphone speakers without the need for DC coupling capacitors used for preventing DC reaching the headphones. An onboard power supply generates a negative voltage rail which powers the output amplifiers, allowing driver amplifier operation from...

20060066410 - Low noise amplifier and related method: A low noise amplifier (LNA) for filtering an input signal to generate an output signal. The low noise amplifier includes a switched loading circuit having a plurality of loading units, each of the loading units determining a corresponding center frequency of the low noise amplifier. The switched loading circuit selectively...

20060066411 - Power amplifier for a transmitter: A power amplifier for a transmitter includes a plurality of CMOS amplifiers of different types which are serially and alternately connected, and matching circuits for matching impedance discrepancies between the CMOS amplifiers of different types....

20060066412 - Ac coupling technique for improved noise performance and simple biasing: A low noise amplifier (LNA), which utilizes an AC coupling technique that can internally bias diodes in such a way as to provide effective low noise amplification, is provided. The low noise amplifier includes an input to an amplifier circuit, and an AC coupling capacitor disposed externally to a chip...

20060055456 - Phase corrected miller compensation of chopper and nested chopper amplifiers: A circuit architecture (200) for implementation of compensation based on Miller capacitors in multi-stage chopped amplifiers includes insertion of an additional chopper (206) in the compensation feedback (118, 120) pathway. Such compensation is more area efficient than parallel compensation and allows higher bandwidth in multistage amplifiers. The insertion of a...

20060055457 - Amplifier circuit: An amplifier circuit includes a first differential amplifier circuit, a second differential amplifier circuit which amplifies an output signal from the first differential amplifier circuit, and an active feedback circuit which performs waveform shaping on the output signal from the first differential amplifier circuit by feeding back an output signal...

20060055458 - Doherty amplifier: The present invention is intended to provide a Doherty amplifier that can accomplish a linear amplifying and a power combining operation closer to the ideal in a simple configuration. The configuration comprises gain compensator 6 that is composed of a parallel circuit made of an anti-parallel diode and a resistor...

20060055459 - Method and apparatus for a linear transconductance device: A transconductance device has substantially linear characteristics. The transconductance device includes a differential pair that receives a differential input voltage signal and produces a differential output current signal and a current source coupled to the differential pair. The current source produces a current having a constant portion and a variable...

20060055460 - Transimpedance amplifier with a high gain/bandwidth product for conversion of a dac output current: The two output currents (INP, IN) which are produced by a current source digital/analog converter (DAC) are supplied to the two halves of a symmetrical transimpedance amplifier. The input current (INP, IN) is supplied to a first stage, which is formed by a first transistor (N2), and a potential at...

20060055461 - Gain control scheme independent of process, voltage and temperature: An apparatus and method to use a shunt network across source terminals of cascode transistors that drive a differential current to control gain. When the gates of the cascode transistors and transistors of the shunt network are activated by a same bias voltage, the gain control is substantially independent of...

20060055462 - Amplifier circuit and gain control method: An amplifier circuit for controlling an output signal is disclosed. The amplifier circuit includes a comparison part for comparing the output signal with a reference voltage and outputting a result of the comparison, and an amplification part for amplifying an input signal with a gain corresponding to the result output...

20060055463 - Linear transconductance cell with wide tuning range: A transconductance cell is disclosed. The transconductance cell may be single-ended or differential. The transconductance cell may include a tunable degeneration circuit. The tunable degeneration circuit may have a plurality of field effect transistors connected in series with each of the field effect transistors having a gate configured to receive...

20060055464 - Travelling-wave amplifier: The invention relates to a travelling-wave amplifier comprising amplifiers and transmission lines. The travelling-wave amplifier provides compensation for the losses of the transmission lines, amplification of the signals and isolation between input and output by coupling the amplifiers to the transmission lines anti-parallel....

20060055465 - Low voltage output current mirror method and apparatus thereof: A current mirror circuit that comprises a current mirror unit, a feedback unit and an amplifier unit is provided to output low voltage. The current mirror unit has a plurality of connecting ends, wherein one end couples to a current source, and the other end couples to a loading device....

20060049869 - Digital amplifier and methods for enhancing resolution and dynamic range of a digital amplifier: An amplifier including a difference amplifier, said difference amplifier including a first output and a second output which are adapted for providing a PWM signal output to a load by signal difference between said first and said second outputs, said difference amplifier being adapted for operating in at least first...

20060049870 - Efficient generation of radio frequency currents: In the present invention, pre-distortion of drive signal and generation of bias signal to a power amplifier are both controlled dependent on an instantaneous size of the input signal, for producing a predetermined gain characteristics. Preferably, the bias signal is kept low in amplitude ranges having a high probability to...

20060049871 - Multi-stage output buffer: A multi-stage output buffer is disclosed having a differential input and a differential output. The output buffer includes an emitter follower circuit coupled to the differential input that is configured to provide a substantially high input impedance at an input thereof, and provide a substantially low output impedance at an...

20060049872 - Non-match power amplifier and method for increased output 1 db compression point: The invention enables an increase in linear power output ranges in a power amplifier by using an unmatched power amplifier driver in place of a matched power amplifier driver....

20060049873 - Rail-to-rail differential input amplification stage with main and surrogate differential pairs: An operational amplifier input stage provides a symmetrical rail-to-rail input common-mode voltage without turning off either pair of complementary differential input transistors. Secondary, or surrogate, transistor pairs assume the function of the complementary differential transistors. The circuit also maintains essentially constant transconductance, constant slew rate, and constant signal-path supply current...

20060049874 - Differential power amplifier and method in class ab mode: The invention enables an increase in linearity of a power amplifier while reducing current consumption by supplying a bias current to the power amplifier in a Class AB mode....

20060049875 - Controllable amplifier circuit with a variable discrete-value gain, use of the amplifier circuit and method for operation of an amplifier whose gain can be adjusted in discrete values: An amplifier circuit is disclosed in which a first amplifier stage and at least one second amplifier stage are each arranged between a signal input and a signal output. These amplifier stages are designed with a first gain factor and with a switching input. The amplifier circuit also has a...

20060049876 - Active circuit having improved linearity using multiple gated transistor: The present invention relates to improved linearity of an active circuit, and more particularly, to an active circuit having improved linearity using a main circuit unit and an assistant circuit unit. According to the present invention, the common gate circuit includes a main circuit unit consisting of a common gate...

20060049877 - High frequency amplifier in an integrated circuit: The invention concerns an integrated circuit amplifier designed to supply an amplified signal at a power of a few hundreds of milliwatts at frequencies from one to several Gigahertz. The final stage of the amplifier comprises two signal amplification input points E and E′ receiving in differential mode a signal...

20060044057 - Class-d amplifier having high order loop filtering: An amplifier having an active and passive gain stage connect to a load for driving a load according to a system analog input. A first embodiment of the amplifier in accordance with the present invention includes a logic network connected between a comparator network and a switching system, wherein the...

20060044058 - Method and circuit for facilitating control of ac coupling in an amplifier circuit: A method and circuit for facilitating control of the AC coupling for addressing input offset in an amplifier circuit are provided. In accordance with an exemplary embodiment, a control circuit comprises a pair of resistive networks coupled together through a capacitive coupling, with the pair of resistive networks configured between...

20060044059 - Feedback circuit: For reducing various adverse effects due to provision of a low-pass filter, while suppressing an oscillation generated therein, there is provide a feedback circuit, having at least one operational amplifier, having a low-pass filter in an output portion thereof, for feeding a signal from the output portion back thereto, including:...

20060044060 - Circuit for parallel operation of doherty amplifiers: A circuit is disclosed for operating Doherty amplifiers in parallel in a small size circuit and at a low cost while reducing transmission loss and preventing a narrowed band. The circuit has a plurality of Doherty amplifiers and a signal combiner. Each of the plurality of Doherty amplifiers is applied...

20060044062 - Amplifying device: An amplifying device comprising a first terminal to which an alternating signal is inputted; a second terminal connected via an external first resistor to a power supply line; a third terminal to be grounded; a second resistor provided on a signal line in between the second terminal and the third...

20060044061 - Analog delay chain having more uniformly distributed capacitive loads and analog delay cell for use in chain: A tapped delay chain comprises a plurality of delay cells where each cell has at least two output taps: a primary one for feeding forward a delayed signal to a next cell in the chain, and a secondary output tap for feeding a slightly-differently delayed signal to a multiplier unit...

20060044063 - Amplifier system and method: An amplifier system comprises an amplifier, a comparator connectable to the amplifier to compare an incoming signal with a number of reference potentials. A switching stage is controlled by the output of the comparator and arranged to select a voltage level to be applied to one side of a load,...

20060044064 - Low noise amplifier: A low noise amplifier is provided that includes a first circuit block capable of amplifying a first voltage signal that is input to the amplifier. The first circuit block includes a first terminal coupled to a first supply voltage by a variable resistance, and a second terminal coupled to a...

20060044065 - Agc circuit: An AGC circuit includes: a variable gain amplifier circuit having a gain controlled with a gain control signal; a rectifier circuit for rectifying an output signal of the variable gain amplifier circuit; a voltage comparator for comparing a rectified signal with a threshold voltage; an up/down counter that switches between...

20060044066 - Cmos amplifiers with frequency compensating capacitors: The frequency and transient responses of a CMOS differential amplifier are improved by employing one or more compensating capacitors. A compensating capacitor coupled to a differential input of the CMOS differential amplifier is used to inject current into the differential input, such that the net current flow through the gate-to-drain...

20060044067 - High-frequency power amplifier: In a high-frequency power amplifier of the present invention, when a short circuit occurs between a gate or source or between a base and emitter in one of unit cells comprising a multi-cell, influence on the operations of the other normal unit cells is suppressed by a direct-current interrupting characteristic...

20060044068 - Bipolar differential to single ended transfer circuit with gain boost: A differential to single-ended signal transfer circuit that allows increased gain and improved AC performance while reducing power supply voltage requirements. The transfer circuit includes a first operational transconductance amplifier (OTA), a second operational amplifier (OPA), first and second controlled current sources, a third current source, and first and second...

20060044069 - Single-ended pseudo-differential output driver: A differential pair of transistors includes a first transistor and a second transistor having their sources coupled together. Their sources are further coupled to ground via a pull-down network. A single-ended output is coupled to the drain of the second of the pair of differential transistors. A differential current adjust...

20060044070 - Signal determining apparatus including amplifier circuit with variable response speed: In a signal determining apparatus including an amplifier circuit adapted to receive and amplify an input signal to generate an output voltage, and a comparator adapted to compare the output voltage of the amplifier circuit with a reference voltage to generate an output signal, the amplifier circuit has variable response...

20060044071 - Sliding cascode circuit: Described techniques extend (e.g., by a factor of 2) the dynamic range of voltage swing for amplifiers and other integrated circuits (e.g., buffers) that are fabricated using lower voltage rated semiconductor processes. Such processes include, for instance, thin gate oxide MOS, and other semiconductor processes that provide desirable features that...