Abstract: A first FET is inserted in a series position between a signal input terminal and a signal output terminal, while second and third FETs are inserted in a shunt position respectively between the signal input terminal and a ground terminal and between the signal output terminal and a ground terminal. First and second reference voltage terminals and a control terminal are provided. A first reference voltage and a control voltage are applied to the first FET, while a second reference voltage and a control voltage are applied respectively to the second and third FETs, so that the first, second, and third FETs serve as variable resistors. As such, a gain control circuit is constructed. Further, a first resistor is provided in parallel to the first FET, while second and third resistors are provided respectively in series to the second and third FETs.

Abstract: Variable attenuation systems having continuous input steering may be used to implement vector or quadrature modulators and vector multipliers. Discrete implementations of attenuators with continuous input steering may have two outputs which may be cross-connected to provide four-quadrant operation. A symmetrically driven center tap may provide improved zero-point accuracy.

Abstract: An adaptively tuned RF power amplifier includes at least one power amplifier stage that has one or more active elements. A tunable output network is coupled to the power amplifier stage and includes one or more adjustable reactive elements. A mismatch detector detects a tuning mismatch based, at least in part, on one or more signals present within the tunable output network, and supplies one or more mismatch signals indicative of a detected tuning mismatch. A tuning controller, responsive to the one or more mismatch signals, controls one or more of the one or more adjustable reactive elements in the tunable output network so as to control the detected mismatch.

Abstract: In a method and apparatus for compensating for gain changes in an amplifier circuit comprising radio-frequency modules and attenuation elements, a radio-frequency module is driven with a first temperature-dependent monitoring voltage UHF(T), and an attenuation element with a second temperature-dependent monitoring voltage UVG(T). The first temperature-dependent monitoring voltage UHF(T) is produced by applying a temperature dependency to an individual monitoring voltage Uopt, which is predetermined for a predetermined temperature for a radio-frequency module, in order to set the optimum operating point of the radio-frequency module. The second temperature-dependent monitoring voltage UVG(T) is produced by applying a temperature dependency to a predetermined monitoring voltage UVG—T for the attenuation element. The monitoring voltage UVG—T is determined in an iteration method, such that the output power of the amplifier circuit reaches a predeterminable level at a constant input power.

Abstract: An apparatus is provided for attenuating electrical signals in the signal path of an electronic audio frequency amplifier for amplifying signals from musical instruments. In accordance with a preferred embodiment, the apparatus is configured to be coupled to the amplifier in more than one arrangement and the apparatus exhibits different attenuation characteristics depending on which arrangement is used to couple the apparatus to the amplifier.

Abstract: Disclosed is a step variable gain amplifier for linearly amplifying a signal received from an antenna. The step variable gain amplifier includes: an amplification unit for converting and amplifying a voltage component of a received signal into a current voltage according to a step amplification control signal; a controller for generating a step amplification control signal of the received signal and controlling on/off of the amplification unit according to the control signal; and an output unit connected to the amplification unit, the output unit outputting a voltage component from the signal that has been subjected to conversion into the current component and amplification processes.

Abstract: Automatic Gain Control AGC circuit comprising a PIN-diode attenuator having an input and an output and a control circuit connected to the attenuator so as to read a signal at the attenuator output. The control circuit is configured to supply a feedback control signal to the attenuator based on an error signal between the signal read at the attenuator output and a reference signal, so as to modulate an attenuation level of said attenuator and maintain a substantially constant power level at the attenuator output. The control circuit particularly comprises at least a resistor and a capacitor which define a time constant of the AGC circuit, so that the AGC circuit features a main pole depending on such time constant and on a voltage of the feedback control signal. The control circuit also comprises a variable gain block, which receives the feedback control signal and which is configured to modulate the main pole proportionally to a variable gain (G) of the gain block.

Abstract: A variable gain amplifier which includes a plurality of individual amplifiers and variably controls the gain by switching to and using one of the individual amplifier circuits includes an individual amplifier (11) which amplifies a signal input from the input terminal of the variable gain amplifier (100) by an active element (M1), and outputs the input signal, an attenuator (14) which attenuates the input signal by a passive circuit (ZC), and outputs the input signal as an attenuated signal, and a virtual ground point providing circuit (15) which provides a virtual ground potential to the input terminal of the virtual ground point providing circuit (15) by an isolation active circuit (MC) interposed between the input terminal of the virtual ground point providing circuit (15) and the ground node of the variable gain amplifier (100).

Abstract: Provided are a gain control device and an amplifier using the gain control device. The gain control device includes a first input resistance unit having a first variable resistor whose resistance is linearly variable and a first fixed resistor respectively receiving a first input signal and a second input signal having a sign different from the first input signal and outputting current through a first output terminal, and a second input resistance unit having a second fixed resistor and a second variable resistor whose resistance is linearly variable respectively receiving the first input signal and the second input signal and outputting current through a second output terminal. Since the gain control device can separately perform dB-linear gain control, it is easily combined with a circuit, such as a continuous-time sigma-delta modulator (SDM), a continuous-time filter, and a continuous-time analog-to-digital converter (ADC), and enables miniaturization and low power consumption.

Abstract: An integrated circuit device includes an amplifier circuit that includes first to Nth amplifiers, an A/D converter, first to Nth offset adjustment registers that are provided corresponding to the first to Nth amplifiers and store first to Nth offset adjustment data, first to Nth D/A converters provided corresponding to the first to Nth amplifiers, first to Nth offset value storage sections that store first to Nth offset value data, and a control circuit that calculates the first to Nth offset adjustment data based on the first to Nth offset value data, and sets the first to Nth offset adjustment data in the first to Nth offset adjustment registers.

Abstract: Provided is a circuit to perform single-ended to differential conversion while providing common-mode voltage control. The circuit includes a converter to convert a single-ended signal to a differential signal and a stabilizing circuit adapted to receive the differential signal. The stabilizing circuit includes a sensor configured to sense a common-mode voltage level of the differential signal and a comparator having an output port coupled to the converter. The comparator is configured to compare the differential signal common-mode voltage level with a reference signal common-mode voltage level and produce an adjusting signal based upon the comparison. The adjusting signal is applied to the converter via the output port and is operative to adjust a subsequent common-mode voltage level of the differential signal.

Abstract: An amplifier includes steering stages to receive a control signal and collectively provide an output signal. Each steering stage receives an associated input signal and contributes to the output signal based on the control signal. The amplifier includes an attenuator to selectively attenuate the input signals to form different gain control ranges for the amplifier.

Abstract: By connecting an antenna damping circuit (4) and a bypass switch (5) in series and connecting the series circuit and an LNA (3) in parallel, it is possible to inhibit a generation of a signal path for connecting the bypass switch (5) to the LNA (3) in series in an operation of the LNA (3) and to prevent a noise factor of the LNA (3) from being deteriorated due to an on resistance of the bypass switch (5).

Abstract: An input stage receives a differential input signal at first and second input nodes and provides a differential output current at first and second output nodes. The differential output current includes a component taken from the input nodes through first and second impedances, and an additional component generated in response to a sample of the voltage of the differential input signal. A transconductance cell having cross-coupled inputs may generate the additional component of the output current.

Abstract: A variable attenuator having: an input port; a semiconductor device having a control electrode for controlling carriers flowing between a first electrode and a second electrode, such control electrode being coupled to one of the first and second electrodes, one of the first and second electrodes being coupled to the input port and the other one of the first and second electrodes being coupled to a reference potential to form an active device characterized by such device having a resistivity in the device to the flow of carriers substantially constant when such device is fed through input port with a signal having a relatively small power level and having a resistivity in the device to the flow of carriers which is nonlinear when such device is fed through input port with a signal having a relatively large power level; and an output port coupled to one of the first and second electrodes coupled to the input port.

Abstract: The present invention relates to a variable gain amplifier. The variable gain amplifier in an ultrasound includes an attenuator. The attenuator includes resistor strings each having a plurality of resistors connected in series to each other and a gain control unit. The gain control unit has tap inputs taken from a plurality of junctions between a first resistor string receiving a first input signal and a second resistor string receiving a second input signal. The gain control unit is configured to provide an attenuated differential input signal based on the tap inputs. The variable gain amplifier includes an amplifying unit having a feedback amplifying section configured to amplify the attenuated differential input signal to output a first amplified signal and a clipping amplifying section configured to amplify the first amplified signal to output a second amplified signal that falls within a predetermined voltage range.

Abstract: Various example embodiments are disclosed. According to one example embodiment, a high bandwidth, fine granularity variable gain amplifier (“VGA”) may comprise an attenuator, a gain block and a gain adjustment control. The attenuator may comprise at least one pair of attenuator differential input nodes and at least one pair of attenuator differential output nodes. The gain block may comprise at least one pair of gain block differential input nodes coupled to the at least one pair of attenuator differential output nodes and at least one pair of gain block differential output nodes. The gain adjustment control may be configured to adjust a gain of the gain block.

Abstract: An amplifier circuit has an amplifier element having an amplifier element input and an amplifier element input impedance, an amplification adjuster adapted to adjust an amplification of the amplifier element, an amplifier circuit input coupled to the amplifier element input, an impedance element having a alterable impedance value and being coupled to the amplifier circuit input, and an impedance adjuster adapted to adjust the impedance value of the impedance element as a function of the amplification of the amplifier element.

Abstract: Systems and methods for performance improvements in digital switching amplifiers using low-pass filtering to reduce noise and distortion. In one embodiment, a digital pulse width modulation (PWM) amplifier includes a signal processing plant configured to receive and process an input audio signal. The amplifier also includes a low-pass filter configured to filter audio signals output by the plant. The filtered output of the plant is added to the input audio signal as feedback. The plant may consist of a modulator and power switch, a noise shaper, or any other type of plant. An analog-to-digital converter (ADC) may be provided to convert the output audio signal to a digital signal. Filtering may be implemented before or after the ADC, and a decimator may be placed after the ADC if it is an oversampling ADC.

Abstract: Method for a variable-gain amplifier (VGA). A plurality of attenuator nodes is serially connected via a first set of resistors between adjacent attenuator nodes to form an attenuator ladder and coupled to an AC input of the variable-gain amplifier. Each of the attenuator nodes includes a transistor and an RC circuitry that couples drain, gate, and source terminals of the transistor to a control signal for the attenuator node. The VGA also includes an amplifier that has an output produced based on an input to the amplifier connected to a plurality of coupled terminals, each of which is respectively from one of the plurality of attenuator nodes.

Abstract: The invention relates to the field of signal processing. It is an object of the invention to provide for limitation of a signal voltage to a predetermined maximum voltage (Vmax). To this end, an input signal (Vin) is applied to a voltage divider which includes a variable-resistance component (T1) whose resistance is controlled by a control signal. An output signal (Vin?) is picked-up at the variable-resistance component (T1). The control signal is generated as an amplified difference between the output signal (Vin?) and a fixed reference voltage (Vmax/2), so that for an “overvoltage case” in which the value of the input signal (Vin) exceeds that of a predetermined maximum voltage (Vmax) the output signal (Vin?) is kept substantially constant.

Abstract: Method for a variable-gain amplifier (VGA). A plurality of attenuator nodes is serially connected via a first set of resistors between adjacent attenuator nodes to form an attenuator ladder and coupled to an AC input of the variable-gain amplifier. Each of the attenuator nodes includes a transistor and an RC circuitry that couples drain, gate, and source terminals of the transistor to a control signal for the attenuator node. The VGA also includes an amplifier that has an output produced based on an input to the amplifier connected to a plurality of coupled terminals, each of which is respectively from one of the plurality of attenuator nodes.

Abstract: An amplifier includes an amplifier module coupled to an input node, and an attenuating module. The attenuating module includes an attenuation resistor coupled to the input node, and an impedance compensation module coupled to the input node. The impedance compensation module compensates an input impedance when an input RF signal is attenuated by the attenuating module.

Abstract: A power amplifier circuit includes a first variable gain amplifier for amplifying an input signal, a second variable gain amplifier for amplifying an output signal of the first amplifier, and a control circuit for controlling the gain of the first variable gain amplifier based on the output signal of the first variable gain amplifier and the gain of the second variable gain amplifier.

Abstract: In a portable radio transceiver, a power amplifier system includes a saturation detector that detects power amplifier saturation in response to duty cycle of the amplifier transistor collector voltage waveform. The saturation detection output signal can be used by a power control circuit to back off or reduce the amplification level of the power amplifier to avoid power amplifier control loop saturation.

Abstract: A wide-band adjustable gain low-noise amplifier (LNA) is disclosed. In various embodiments, the LNA includes a first inverting amplifier configured to generate a first intermediate signal. A first attenuator is configured to receive the first intermediate signal and to generate a second intermediate signal. In various embodiments, the LNA includes a second attenuator configured to generate a third intermediate signal. A second inverting amplifier is configured to generate a fourth intermediate signal using the third intermediate signal. A summing circuit is configured to generate an output signal based on the second and the fourth intermediate signals. Apparatus and methods according to various embodiments of the invention are also disclosed.

Abstract: A novel digital attenuator circuit and associated pre-power amplifier (PPA) that substantially increases the dynamic range of the amplifier. Increased dynamic range is achieved by placing a digital current attenuator circuit at the output of the pre-power amplifier so that the minimum possible current output of the transistor switch array of the PPA can be further attenuated. The attenuator functions to split the current between the load and the power supply VDD (i.e. AC ground) based on device ratio that is controlled digitally via an input power control word. The digital attenuator is constructed as a segmented digitally controlled matrix or cell array comprising at least a pass and bypass matrix or array. The pass matrix controls the amount of current output from the PPA while the bypass matrix controls the amount of current shorted to the AC ground (i.e. power supply). By varying the number of transistors on or off in each matrix, the power output of the PPA can be easily and accurately controlled.

Abstract: This variable gain amplifier is provided with an operational amplifier. The non-inversion input terminal of the operational amplifier is connected to a reference potential. A feedback resistor is connected between the output terminal and inversion input terminal of the operational amplifier. An input resistor is inserted between the inversion input terminal of the operational amplifier and the input terminal of the variable gain amplifier circuit. An adjustment resistor is connected between the inversion input terminal of the operational amplifier and the reference potential. The resistance value of the adjustment resistor is controlled in such a way as to maintain constant against the resistance value change a combined resistance value in its parallel connection with the input resistor when changing the resistance value of the input resistor.

Abstract: Circuitry to remove switches from signal paths in integrated circuit programmable gain attenuators. Programmable gain attenuators and programmable gain amplifiers commonly switch between signal levels using semi-conductor switches. Such switches may introduce non-linearities in the signal. By isolating the switches from the signal path linearity of the PGA can be improved.

Abstract: In one embodiment, the present invention includes an amplifier having an input to receive a radio frequency (RF) signal from an output node of a source. An input stage coupled to the amplifier input may include one or more components to aid in processing of incoming signals. One such component coupled between the source and the input of the amplifier is a coupling capacitor used to maintain a bias voltage of the amplifier at a different potential than a DC voltage of the output node. In certain applications, the amplifier and the coupling capacitor may be integrated on a single substrate.

Abstract: A first FET is inserted in a series position between a signal input terminal and a signal output terminal, while second and third FETs are inserted in a shunt position respectively between the signal input terminal and a ground terminal and between the signal output terminal and a ground terminal. First and second reference voltage terminals and a control terminal are provided. A first reference voltage and a control voltage are applied to the first FET, while a second reference voltage and a control voltage are applied respectively to the second and third FETs, so that the first, second, and third FETs serve as variable resistors. As such, a gain control circuit is constructed. Further, a first resistor is provided in parallel to the first FET, while second and third resistors are provided respectively in series to the second and third FETs.

Abstract: There is provided a variable-gain amplifier, including two cascode amplifiers and an attenuator. The cascode amplifiers are mutually connected in parallel via the attenuator.

Abstract: An attenuator includes one or more series attenuation branches including one or more series field effect transistors (FETs) each having a gate; one or more shunt attenuation branches including one or more shunt FETs each having a gate; and a bias control FET. The bias control FET receives at its gate a first bias control signal and in response thereto produces at one of its drain and source terminals a second bias control signal. Either the first bias control signal is coupled to the gates of one or more series FETs, and the second bias control signal is coupled to the gates of the one or more shunt FETs; or the first bias control signal is coupled to the gates of the one or more shunt FETs, and the second bias control signal is coupled to the gates of the one or more series FETs.

Abstract: A variable-gain amplifier includes an intermediate node operative to receive an electric current from a current source. A common-emitter amplifier has a collector electrically connected to the intermediate node. A first common-base amplifier has an emitter electrically connected to the intermediate node and a collector electrically connected to an output node. A base-degenerated amplifier has an emitter electrically connected to the intermediate node and a collector electrically connected to the output node. A second common-base amplifier has an emitter electrically connected to the intermediate node and a collector electrically connected to small-signal ground.

Abstract: A first FET is inserted in a series position between a signal input terminal and a signal output terminal, while second and third FETs are inserted in a shunt position respectively between the signal input terminal and a ground terminal and between the signal output terminal and a ground terminal. First and second reference voltage terminals and a control terminal are provided. A first reference voltage and a control voltage are applied to the first FET, while a second reference voltage and a control voltage are applied respectively to the second and third FETs, so that the first, second, and third FETs serve as variable resistors. As such, a gain control circuit is constructed. Further, a first resistor is provided in parallel to the first FET, while second and third resistors are provided respectively in series to the second and third FETs.

Abstract: An amplifying transistor for amplifying a radio frequency signal between an input terminal and an output terminal. The cathode of a first diode is connected to the input terminal and the anode of a second diode is connected to the output terminal. A matching and attenuating circuit is connected between the anode of the first diode and the cathode of the second diode. A matching and attenuating circuit reduces impedance mismatches on the input terminal side and the output terminal side, and attenuates the radio frequency signal. In an amplification mode, a bias circuit supplies a bias current to an amplifying transistor and a current mirror circuit turns off the first and second diodes. In an attenuation mode, the bias circuit supplies no bias current to the amplifying transistor and the current mirror circuit turns on the first and second diodes.

Abstract: A millimetric-wave amplifier arrangement comprises a first amplifier whose output is connected to one input of the second amplifier via an adjustable attenuator. Both amplifiers are integrated on a single substrate.

Abstract: Circuitry to remove switches from signal paths in integrated circuit programmable gain attenuators. Programmable gain attenuators and programmable gain amplifiers commonly switch between signal levels using semi-conductor switches. Such switches may introduce non-linearities in the signal. By isolating the switches from the signal path linearity of the PGA can be improved.

Abstract: Electromagnetic compatibility of an information handling system and peripheral for achieving defined electromagnetic interference constraints is tested through a test adapter that interfaces with an external cable connecting the information handling system and peripheral. Signals from the external cable are passed through an isolation resistor and parallel capacitance to compensate for input capacitance of a signal tester. A common mode choke isolates a common mode component of the signal at the external cable. A noise generator applies a signal through the test adapter to the external cable to allow measurement of signals emitted from the peripheral due to injected noise.

Abstract: An integrated circuit device includes an amplifier circuit that receives an input signal and performs an offset adjustment corresponding to a DC offset of the input signal and a gain adjustment corresponding to an amplitude of the input signal, a filter that is provided in a subsequent stage of the amplifier circuit, a cut-off frequency of the filter being variably set corresponding to a frequency band of the input signal, an A/D converter that is provided in a subsequent stage of the filter and performs an A/D conversion process on a signal amplified by the amplifier circuit, and a control circuit that sets an offset adjustment of the amplifier circuit, a gain adjustment of the amplifier circuit, and the cut-off frequency of the filter.

Abstract: An amplifier includes an amplifier module coupled to an input node, and an attenuating module. The attenuating module includes an attenuation resistor coupled to the input node, and an impedance compensation module coupled to the input node. The impedance compensation module compensates an input impedance when an input RF signal is attenuated by the attenuating module.

Abstract: An apparatus for setting an attenuation of an attenuator includes a control transistor, which includes a drain connected to a gate of a shunt transistor of the attenuator. A channel resistance of the shunt transistor corresponds to a current density of the control transistor, and the channel resistance of the shunt transistor determines the attenuation of the attenuator. The current density of the control transistor is based at least in part on a control voltage input to the apparatus.

Abstract: An attenuation compensating circuit includes a detector and a stabilizer. The detector has a dummy capacitor corresponding to a capacitor connected to an input terminal of an amplifier and, by detecting the degree of attenuation of a dummy signal passing through the dummy capacitor, detects the degree of attenuation when a signal to be amplified passes through the capacitor connected to the amplifier. The stabilizer has two dummy amplifiers and causes a voltage difference between the input voltages of the dummy amplifiers, where the voltage difference corresponds to the degree of attenuation detected by the detector. The stabilizer controls a bias voltage for setting gain of the dummy amplifier so that a product of the voltage difference of the input voltage and the gain of the dummy amplifier is equivalent to the difference of the voltages output by the dummy amplifiers and supplies the bias voltage to the amplifier.

Abstract: A fine granularity, wide-range variable gain amplifier (“VGA”) comprises an attenuator, a high gain signal path, a low gain signal path and a gain adjustment control to adjust a gain of the VGA, wherein the gain adjustment control is configured to cause a selective activation of at least a portion of the low gain signal path or the high gain signal path to achieve a desired overall gain.

Abstract: The invention includes a power amplifier with an amplifier core including parallel amplifier cells, a replica cell made of one amplifier cell similar to those of the amplifier core, a power controller to select a combination of amplifier cells to activate, a regulator to fix the top voltage of the replica cell to a reference voltage, a voltage generator to provide the voltage reference to the regulator, a current generator to provide a reference current through the replica cell, and a drive unit controlled by the regulator output to drive the combination of amplifier cells, so that each selected combination of activated cells defines a predetermined attenuation level of power amplifier output signal so that it is attenuated in a stepwise manner.

Abstract: An amplifying transistor for amplifying a radio frequency signal between an input terminal and an output terminal. The cathode of a first diode is connected to the input terminal and the anode of a second diode is connected to the output terminal. A matching and attenuating circuit is connected between the anode of the first diode and the cathode of the second diode. A matching and attenuating circuit reduces impedance mismatches on the input terminal side and the output terminal side, and attenuates the radio frequency signal. In an amplification mode, a bias circuit supplies a bias current to an amplifying transistor and a current mirror circuit turns off the first and second diodes. In an attenuation mode, the bias circuit supplies no bias current to the amplifying transistor and the current mirror circuit turns on the first and second diodes.

Abstract: A high-frequency circuit is provided. In the high-frequency circuit, a first PIN diode is provided in a signal line and a second PIN diode is provided between the signal line and ground so that an attenuating circuit is formed. A power supply is applied to one end of a series circuit composed of two resistors. The other end of the series circuit is connected to ground via a drain-source path of an FET. An AGC voltage is applied to a gate of the FET. A bias voltage in accordance with the AGC voltage is applied to a base voltage of a low-noise amplifier via the first and second PIN diodes so as t control attenuation of the first PIN diode and an operating current of the low-noise amplifier.

Abstract: By connecting an antenna damping circuit (4) and a bypass switch (5) in series and connecting the series circuit and an LNA (3) in parallel, it is possible to inhibit a generation of a signal path for connecting the bypass switch (5) to the LNA (3) in series in an operation of the LNA (3) and to prevent a noise factor of the LNA (3) from being deteriorated due to an on resistance of the bypass switch (5).

Abstract: A variable gain amplifier of the present invention connects an input and an output of a first variable gain amplifier circuit to an RF input terminal and an RF output terminal, respectively, connects one terminal of an attenuation circuit is to an RF input terminal, connects an input and an output of a second variable gain amplifier circuit to the other terminal of the attenuation circuit and an RF output terminal, respectively, connects one terminal of the variable resistance circuit to a node between the attenuation circuit and the second variable gain amplifier circuit, and grounds the other terminal of the variable resistance circuit. A gain of the first variable gain amplifier circuit, a gain of the second variable gain amplifier circuit, and a resistance value of the variable resistance circuit are then varied by a gain control voltage outputted from a gain control section.

Abstract: A gain compensation circuit comprises a first amplifier, a second amplifier, a filter, a first attenuator, a second attenuator and a third attenuator. The first amplifier is configured to amplify an input signal of the microwave signal processor. The filter is disposed between the first and second amplifiers. The first attenuator is disposed between the first amplifier and the filter for reducing return loss of the microwave signal processor. The second attenuator is disposed between the second amplifier and the filter for reducing return loss of the microwave signal processor. The third attenuator is electrically connected to the output of the second amplifier for reducing noise figure of the microwave signal processor and providing first and second gain compensations. The first gain compensation keeps the gain of the microwave signal processor constant under various temperatures, and the second gain compensation adjusts a nominal gain of the microwave signal processor.