Showing papers on "Cascade amplifier published in 2002"

Multi-wavelength light amplifier

Abstract: A multi-wavelength light amplifier includes a first-stage light amplifier which has a first light amplifying optical fiber amplifying a light input, a second-stage light amplifier which has a second light amplifying optical fiber amplifying a first light output from the first-stage light amplifier, and an optical system which maintains a second light output of the second-stage light amplifier at a constant power level. The first-stage and second-stage light amplifiers have different gain vs wavelength characteristics so that the multi-wavelength light amplifier has no wavelength-dependence of a gain thereof.

Switched gain amplifier circuit

Abstract: An amplifier chain that switches between a saturated mode of operation and a linear mode of operation comprises at least two amplifier stages. A switch is associated with the first amplifier stage and dampens the gain of the amplifier chain when the switch is closed. In a first embodiment, this is done by bypassing the first amplifier stage. In second and third embodiments, this is done by providing a feedback loop to the first amplifier stage. Dynamic device scaling and changing the bias may also be used to affect the performance of the amplifier chain.

System and method for rf signal amplification

Abstract: A branched power amplifier circuit includes two or more amplifier segments or branches, each with a corresponding lossy modulator. The branched power amplifier may be dynamically resized by enabling different ones of its branches to deliver peak efficiency at a number of different amplifier output power levels. Each amplifier branch operates in a saturated mode and selectively amplifies an RF input signal. The lossy modulators provide either supply voltage or supply current modulation to corresponding amplifier branches, thus imparting highly linear amplitude modulation to the overall output signal generated by branched power amplifier, despite its saturated mode operation. The branched power amplifier circuit may be configured such that particular combinations of segments have peak efficiencies matched to the needs of one or more air interface standards used in wireless mobile communication systems.

Power amplifier protection circuit

Abstract: A power amplifier circuit comprises a sensing circuit and a processing circuit adapted to detect voltage peaks in an output of a power amplifier. If the voltage peak is above a predetermined threshold level, the processing circuit acts to reduce bias provided to the power amplifier, thereby reducing the output levels.

Controller for an RF power amplifier

Abstract: The controller controls the amplifier and a modulated power supply, supplying power to the amplifier, by detecting an RF envelope of a signal input to the amplifier. Predistortion of the amplifier synchronous with changes of bias is provided using a look-up table. Specifically, amplitude predistortion, phase predistortion and DC voltage level adjustments are made to the RF signal. Adjustments for gain and phase variation are applied synchronously with bias changes.

Power amplification apparatus of portable terminal

Abstract: The present invention relates to a power amplification circuit of a mobile device for improving the efficiency and the linearity properties of the power amplifier. In one embodiment, the power amplifier improves these properties by controlling the input voltage of the supplemental amplifier so that the power amplifier operates as the Doherty mode in the low output power mode depending on the magnitude of the output power from the output unit and so that the input voltage of the supplemental amplifier may be increased up to satisfy the non-linear operational requirements of a power amplifier in the high output power mode. Moreover, because only the input voltage of the supplemental amplifier is controlled, the power amplifier can be implemented in a simple manner. Thus, the size of the power amplifier becomes small, which in turn reduces the cost of the power amplifier, among other things.

Side-tone control within a telecommunication instrument

Abstract: A side-tone control unit for a telecommunication instrument (1) is configured to include a side-tone amplifier (30) having a transfer function selectively controlled in accordance with a set of amplifier parameters, and a side-tone controller (40), coupled to the side-tone amplifier (30), for selectively applying the set of amplifier parameters to the side-tone amplifier (30) based on the detected energy of an uplink signal and the detected energy of a downlink signal. The side tone controller (40) can select a particular set of amplifier parameters by indexing a table (80) in accordance with quantized values of the detected uplink signal energy and the detected downlink signal energy.

Composite amplifier structure

Abstract: A composite power amplifier structure includes a first power amplifier (PAN+1) configured as an auxiliary amplifier of a Doherty amplifier and connected to an output node and an even number of further power amplifiers configured into at least one Chireix pair (PA 1,1 + PA 1,2 ...PA N,1 + PA N,2) connected to the same output node. The Chireix pairs are driven (40) at least partially in outphasing modes and the first power amplifier is driven (40) in the same manner as the auxiliary amplifier of a Doherty amplifier.

HEMT-HBT doherty microwave amplifier

Abstract: A microwave amplifier and more particularly to a microwave amplifier configured as a Doherty amplifier. The amplifier includes a carrier amplifier, a peak amplifier, a Lange coupler at the input of the amplifiers and quarter wave amplifier at the output of the amplifiers. In order to further increase the efficiency, the Doherty amplifier is formed from HEMT/HBT technology to take advantage of the low-noise performance of HEMTs and the high-linearity of HBTs to form a relatively efficient amplifier that functions as a low-noise amplifier at low power levels and automatically switches to high-power amplification for relatively high-impact RF power levels.

Asymmetrically biased high linearity balanced amplifier

Abstract: A microwave amplifier and more particularly to a microwave amplifier configured as a Doherty amplifier. In particular, the amplifier includes a carrier amplifier, a peak amplifier a Lange coupler at the input of the amplifiers and quarter wave amplifier at the output of the amplifiers. In order to improve isolation between the amplifiers to minimize the dependence of each amplifier's inter-modulation (IM) performance on the others, matching networks are provided, coupled to the output of the amplifiers. In addition, the microwave power amplifier includes electronic tuning which allows for improved inter-modulation distortion over a wide input power dynamic range, which allows the IM performance of the microwave amplifier to be adjusted for the operating frequency of the amplifier.

A high-power Ka-band quasi-optical amplifier array

Abstract: Results for a high-power Ka-band quasi-optical amplifier array are presented in this paper. The amplifier consists of a 45-element double-sided active array with a hard-horn feed. Excess heat is removed via a metal carrier integrated into the array with liquid cooling at the periphery. Each unit cell of the array consists of transmitting and receiving patch antennas, driver and power amplifier monolithic microwave integrated circuits on input and output layers, and a through-plate coaxial transition, which connects the input and output layers. An estimated 25 W is radiated when the amplifier is used as an antenna feed, otherwise 13 W is collected into waveguide. Experimental results and construction details are discussed.

Multiple bandwidth amplifier control systems for mobile stations and methods therefor

Abstract: RF amplifier control circuits for transmitters in mobile communication devices, combinations thereof and methods therefor. The control circuits include generally proportional and integral control circuits having an output coupled to a control input of an amplifier (110). An initial control signal is applied to the amplifier before a vector modulator output (120) coupled an input thereof is at full output power. The vector modulator output is ramped to full output after applying the initial control signal. Thereafter, the initial control signal applied to the amplifier during ramping is corrected by integrating an output of the amplifier relative to a second reference signal with an integral control circuit coupled to the control input of the amplifier, the second reference signal is proportional to the ramping vector modulator output.

Current probe device having an integrated amplifier

Abstract: A measurement system is provided that includes a probe device having an integrated amplifier. The integrated amplifier may be a transimpedence amplifier that amplifies input current to an output voltage.

Composite amplifier with optimized linearity and efficiency

Abstract: The invention relates to a composite amplifier (500) based on a main amplifier (510) and an auxiliary amplifier (520), and compensation for non-linear amplifier behavior by means of respective non-linear models (570, 575) of parasitics. In order to provide proper excitation of the non-linear models, a filter network (560) based on a linear model of the output network of the composite amplifier is provided. The linear filter network (560) basically determines ideal output node voltages, which are used as input to the respective non-linear models for generating appropriate compensation signals. The compensation signals are finally merged into the input signals of the respective sub-amplifiers (510, 520), thus effectively compensating for the effects of the non-linear parasitics.

Bias adjustment for power amplifier

Abstract: A power amplifier having bias that may be automatically adjusted based on a detected output power level. The amplifier includes one or more amplifier stages operatively coupled to a control unit. The amplifier stage(s) couple together (e.g., in series) and recive and amplify an RF input signal to provide an RF output signal. A power detector detects the RF output signal level (or power) and provides a detected signal. A control unit conditions the detected signal (e.g., with a particular transfer characteristic) to provide at least one conditioned signal. A bias control generator receives the conditioned signal(s) and provides at least one bias control signal, with each bias control signal used to adjust the bias of a respective amplifier stage. The bias adjustment is performed in a manner to achieve the desired level of linearity while minimizing power consumption.

Transmitter with transmitter chain phase adjustment on the basis of pre-stored phase information

Abstract: A transmitter chain has a quadrature modulator, a variable gain amplifier, an up-converter, and a variable gain power amplifier. An overall phase of the transmitter chain is adjusted on the basis of pre-stored phase information reflecting phase changes due to simultaneous gain changes of gains of at least the variable gain amplifier and the variable gain power amplifier.

Dual mode power supply

Abstract: A battery (102) powers a wireless telephone's power amplifier (106) through a Switch Mode Power Supply (SMPS) (104). The SMPS has a capacity lower than the maximum power requirements of the amplifier. When a controller (116) senses that an amplifier power-requirements threshold has been exceeded, it closes a switch (114) parallel to the SMPS, allowing power to flow from the battery to the amplifier without passing through the SMPS. This architecture allows the use of a smaller SMPS, and eliminates SMPS-generated noise to the amplifier when the amplifier is least able to tolerate such noise, namely, under high power conditions.

Effect of amplifier parameters on single-event transients in an inverting operational amplifier

Abstract: Laser data and simulation tools are combined to investigate the single-event transient response of the LM124 operational amplifier. The effect of the bandwidth and gain on transients originating in different stages in the operational amplifier is studied. We found that the single-event transient response of the LM124 operational amplifier in an inverting configuration was dependent on the bandwidth of the amplifier, the gain, and on the values of the resistors used to program the gain of the amplifier. We show the results of simulations which illustrate how these changes impact the single-event transient response of the amplifier. An analysis of the results suggests which properties of an operational amplifier will provide a better single-event transient response.

A power amplifier module with distortion compensation

Abstract: The invention relates to a power amplifier module comprising a first amplifier (2) having a first front-end (4) and a first backend amplifier stage (5) and a second amplifier (3) having a second front-end (6) and a second backend amplifier stage (7), the first amplifier and the second amplifier being arranged in a Bridge Tied Load (BTL) configuration with feedback over the load, characterized in that the first and the second backend amplifier stages having point symmetrical transfer functions with respect to the origin, the input current i1 of the first backend amplifier stage being substantially equal to the input current i2 of the second backend amplifier stage.

Full output matching apparatus of a microwave doherty amplifier

Abstract: Quarter wave transformers are connected to final outputs of a carrier amplifier and a peaking amplifier, which are coupled in parallel to each other, so as to induce a Doherty operation of a microwave Doherty amplifier. Load matching circuits for obtaining a microwave output matching are connected to output terminals of the carrier amplifier and the peaking amplifier. A phase tuning component is positioned behind the load matching circuit. Accordingly, a matching state can be maintained without being changed at a high power level but can be adjusted depending on phase variations at a low power level to attain efficiency enhancements and optimum linearity.

Distributed amplifier having separately biased sections

Abstract: A distributed amplifier (40) comprising an input transmission line (48), an output transmission line (50) and N amplifier sections (42,44,46), and N biasing sources (82) configured to provide N independent biasing voltages for each transistor (52) of the N amplifier sections (42,44,46) for active operation as such that when a first independent biasing voltage of a first transistor is modified the first transistor is configured for a non-active operation and an output power of the distributed amplifier (40) is reduced without a substantial degradation in an efficiency of the distributed amplifier (40).

Ultrahigh-efficiency power amplifier for space radar applications

Abstract: This paper describes a broad-band switch mode power amplifier based on the indium phosphide (InP) double heterojunction bipolar transistor (DHBT) technology. The amplifier combines the alternative Class-E mode of operation with a harmonic termination technique that minimizes the insertion loss of matching circuitry to obtain ultrahigh-efficiency operation at X-band. For broad-band Class-E performance, the amplifiers output network employs a transmission line topology to achieve broad-band harmonic terminations while providing the optimal fundamental impedance to shape the output current and voltage waveforms of the device for maximum efficiency performance. As a result, 65% power-added efficiency (PAE) was achieved at 10 GHz. Over the frequency band of 9-11 GHz, the power amplifier achieved 49%-65% PAE, 18-22 dBm of output power, and 8-11 dB gain at 4 V supply. The reported power amplifier achieved what is believed to be the best PAE performance at 10 GHz and the widest bandwidth for a switch-mode design at X-band.

Switchable gain amplifier

Abstract: A switchable gain amplifier for use in mobile communications devices is provided, having a first amplifier stage having a first gain, a second amplifier stage connected in parallel with the first amplifier stage. The first and second amplifier stage have different gains and a gain controller, connected to the first amplifier stage and to the second amplifier stage, enables only one of the amplifier stages at a time.

Control architecture and method for optical amplifiers

Abstract: A method of controlling an optical amplifier (100) by receiving a portion of the intput signal (101) to the optical amplifier and receiving a portion of an output signal (113) of the amplifier. Both amplification stages (106, 112) are adjusted based on the received portions.

Automatic optimization of linearity for envelope feedback rf amplifier linearization

Abstract: An amplifier configuration and method of amplifying a signal are provided for automatic optimization of linearity of power amplifier input/output characteristics. The amplifier configuration utilizes a feedback loop that includes detecting envelopes of signals that are input and output from a power amplifier. The amplifier configuration includes an offset parameter determined in a second feedback loop that adapts to values for optimizing the linearity of the power amplifier output when input signal amplitudes are within a predetermined range of small signal values, thereby producing a substantially reduced distortion and thus linearized output over the entire input signal amplitude range.

Ping-pong amplifier with auto-zeroing and chopping

Abstract: A ping-pong amplifier employs auto-zeroing and chopping to simultaneously achieve low offset voltage and low frequency noise, as well as low energy at the chopping frequency. The ping-pong amplifier includes respective nulling amplifiers (A3, A4) for each of its gain amplifiers (A1, A2), which auto-zero each gain amplifier. In addition, switches are included which allow the inputs and outputs of the active gain amplifier to be chopped. Thus, while one gain amplifier is being auto-zeroed, the other gain amplifier amplifies the input signal and its inputs and outputs are chopped. One of the described embodiments includes circuitry which reduces switching transients that might otherwise appear in the amplifier's output by ensuring that the common-mode output voltage of each gain amplifier is kept equal to a common-mode reference voltage.

A low power fully integrated bandpass operational amplifier for biomedical neural recording applications

Abstract: This paper presents a low power fully integrated bandpass amplifier for a variety of biomedical neural recording applications. A standard two-stage CMOS amplifier in a closed-loop resistive feedback configuration provides stable AC gain of 39.5 dB at 1 kHz. A PMOS input transistor, biased near the sub-threshold region acting as a high value resistor in the range of hundreds of mega ohms, is utilized to clamp the large and random DC open circuit potential that normally exists at the electrode-electrolyte interface. The 3 dB bandwidth of the amplifier is measured to be 26 Hz - 6.5 kHz and the tolerable DC input range is measured to be at least 1 V. The amplifier measures 0.107 mm/sup 2/ in die area and dissipates 133 /spl mu/W from a 3 V power supply. It is fabricated in MOSIS AMI 1.5 /spl mu/m double poly double metal n-well CMOS process. Bench tests show complete functionality of the amplifier in both light and dark conditions and for a wide range of recording electrode capacitance.

Sense amplifier for multilevel non-volatile integrated memory devices

Abstract: A sense amplifier (100) useable with memories having multi-level memory cells (105) includes a cascode device (135) coupled to the cell (105) to increase sense amplifier resolution. In a pre-charge mode, the sense amplifier (100) is configured to pre-charge a bit-line (140) of the cell (105) to reduce time required to read the cell. The pre-charge mode may include a unity gain buffer (175) to which a reference voltage is applied, and a switch (165, 170). The switch (165, 170) couples the buffer to the cascode device (135) to pre-charge the bit-line (140), and decouples the buffer from the device to enable the amplifier (100) to develop a voltage signal representing data stored in the cell. The sense amplifier (100) can be re-configured in a regeneration mode to amplify the voltage signal, to conserve chip space, and reduce cost and errors in reads.

High-frequency power amplifying apparatus

Abstract: A high-frequency power amplifying apparatus includes a plurality of series-connected amplifiers, a power controller for selectively supplying an output terminal with an output from a desired one amplifier in accordance with a demanded output power and for causing one or more amplifiers downstream of the desired one amplifier to be in a cutoff state, and an output delay line connected between the output terminal and the final-stage amplifier and having a line length thereof providing the final-stage amplifier with a high impedance as viewed from the output terminal when the final-stage amplifier is in a cutoff state.