Showing papers on "Amplifier published in 1999"

Design of Analog CMOS Integrated Circuits

Abstract: The CMOS technology area has quickly grown, calling for a new text--and here it is, covering the analysis and design of CMOS integrated circuits that practicing engineers need to master to succeed. Filled with many examples and chapter-ending problems, the book not only describes the thought process behind each circuit topology, but also considers the rationale behind each modification. The analysis and design techniques focus on CMOS circuits but also apply to other IC technologies. Table of contents 1 Introduction to Analog Design 2 Basic MOS Device Physics 3 Single-Stage Amplifiers 4 Differential Amplifiers 5 Passive and Active Current Mirrors 6 Frequency Response of Amplifiers 7 Noise 8 Feedback 9 Operational Amplifiers 10 Stability and Frequency Compensation 11 Bandgap References 12 Introduction to Switched-Capacitor Circuits 13 Nonlinearity and Mismatch 14 Oscillators 15 Phase-Locked Loops 16 Short-Channel Effects and Device Models 17 CMOS Processing Technology 18 Layout and Packaging

RF Power Amplifiers for Wireless Communications

Abstract: Linear PA Design. Conventional High-Efficiency Amplifier Modes. Class AB PAs at GHz Frequencies. Practical Design of Class AB PAs. Overdrive and the Class F Mode. Switching Mode Amplifiers for RF Applications. Switching PA Modes at GHz Frequencies. Signals, Modulation Systems, and PA Nonlinearities. Efficiency Enhancement Techniques. Power Amplifier Bias Circuit Design. Power Amplifier Architecture. PA Linearization Techniques.

The Physics of Free Electron Lasers

Abstract: Introduction.- One-Dimensional Theory of the FEL Amplifier.- One-Dimensional Theory of the FEL Oscillator.- Diffraction Effects in the FEL Amplifier.- Waveguide FEL.- FEL Amplifier Starting from Shot Noise.- Appendices.- References.- Index

Pump interactions in a 100-nm bandwidth Raman amplifier

Abstract: A design for a 100-nm bandwidth Raman amplifier is presented. The amplifier is pumped with eight, 130-mW lasers with wavelengths ranging from 1416 to 1502 nm. The peak-to-peak gain ripple is 1.1 dB. A new model was developed for this design that includes pump-to-pump and signal-to-signal interactions in addition to double Rayleigh scattering and amplified spontaneous emission. An understanding of the interactions among these various effects was essential to this design. These modeling results are based on measurements of the physical characteristics of the transmission fiber.

High-efficiency power amplifier using dynamic power-supply voltage for CDMA applications

Abstract: Efficiency and linearity of the microwave power amplifier are critical elements for mobile communication systems. This paper discusses improvements in system efficiency that are obtainable when a DC-DC converter is used to convert available battery voltage to an optimal supply voltage for the output RF amplifier. A boost DC-DC converter with an operating frequency of 10 MHz is demonstrated using GaAs heterojunction bipolar transistors. Advantages of 10 MHz switching frequency and associated loss mechanisms are described. For modulation formats with a time-varying envelope, such as CDMA, the probability of power usage is described. Gains in power efficiency and battery lifetime are calculated. An envelope detector circuit with a fast feedback loop regulator is discussed. Effects of varying supply voltage with respect to distortion are examined along with methods to increase system linearity.

Impact of amplifier nonlinearities on OFDM transmission system performance

Abstract: The power spectral density of an orthogonal frequency-division multiplexing (OFDM) signal after a saturated high-power amplifier (HPA) is analytically derived. The distortion of the HPA-processed OFDM signal is defined, and its power spectrum is computed. The spectra of the signal and of the distortion are used to get an accurate estimate of the bit-error rate of an OFDM transmission system and to derive compensation at the receiver, which leads to performance improvement.

A 1.9-GHz, 1-W CMOS class-E power amplifier for wireless communications

Abstract: This paper presents a 1-W, class-E power amplifier that is implemented in a 0.35-/spl mu/m CMOS technology and suitable for operations up to 2 GHz. The concept of mode locking is used in the design, in which the amplifier acts as an oscillator whose output is forced to run at the input frequency. A compact off-chip microstrip balun is also proposed for output differential-to-single-ended conversion. At 2-V supply and at 1.98 GHz, the power amplifier achieves 48% power-added efficiency (41% combined with the balun).

Method and apparatus for operating a radio-frequency power amplifier as a variable-class linear amplifier

Abstract: A variable-class linear amplifier (600, 800, 900) applies a supply type of envelope modulation to an RF power amplifier operating in or near compression at highest envelope amplitudes, and transitions gradually to an envelope tracking type of operation at intermediate envelope amplitudes. The amplifier further transitions gradually to a linear class of operation with a constant supply voltage (508) at lowest envelope amplitudes.

Distortion in elementary transistor circuits

Abstract: In this paper the distortion components are defined for elementary transistor stages such as a single-transistor amplifier and a differential pair using bipolar transistors or MOSTs Moreover, the influence of feedback is examined Numerical examples are given for sake of illustration

An 8-bit 150-MHz CMOS A/D converter

Abstract: This paper describes an 8-bit 5-stage pipelined and interleaved analog-to-digital converter that performs analog processing only by means of open-loop circuits such as differential pairs and source followers to achieve a high conversion rate. The concept of sliding interpolation is proposed to obviate the need for a large number of comparators or interstage digital-to-analog converters and residue amplifiers. The pipelining scheme incorporates distributed sampling between the stages so as to relax the linearity-speed tradeoffs in the sample-and-hold circuits, A clock edge reassignment technique is also introduced that suppresses timing mismatches in interleaved systems, and a punctured interpolation method is proposed that reduces the integral nonlinearity error with negligible speed or power penalty. Fabricated in a 0.6-/spl mu/m CMOS technology, the converter achieves differential and integral nonlinearities of 0.62 and 1.24 LSB, respectively, and a signal-to-(noise+distortion) ratio of 43.7 dB at a sampling rate of 150 MHz. The circuit draws 395 mW from a 3.3-V supply and occupies an area of 1.2/spl times/1.5 mm/sup 2/.

A linear amplifier arrangement

Abstract: An amplifier arrangement comprising an amplifier for amplifying an input radio frequency (RF) signal to generate an output RF signal. A linear function processor generates a linear function correction signal which is a linear function of previous samples of the input signal in order to compensate for distortion effects of the amplifier related to the history of the input signal. A non-linear function processor generates a non-linear function of the input signal in order to compensate for instantaneous distortion effects of the amplifier. Then a pre-distortion processor distorts the current input signal in accordance with the linear and non-linear function correction signals in order to compensate for both types of distortion in the output signal.

2.5-THz GaAs monolithic membrane-diode mixer

Abstract: A novel GaAs monolithic membrane-diode (MOMED) structure has been developed and implemented as a 2.5-THz Schottky diode mixer. The mixer blends conventional machined metallic waveguide with micromachined monolithic GaAs circuitry to form, for the first time, a robust, easily fabricated, and assembled room-temperature planar diode receiver at frequencies above 2 THz. Measurements of receiver performance, in air, yield at T/sub receiver/ of 16500-K double sideband (DSB) at 8.4-GHz intermediate frequency (IF) using a 150-K commercial Miteq amplifier. The receiver conversion loss (diplexer through IF amplifier input) measures 16.9 dB in air, yielding a derived "front-end" noise temperature below 9000-K DSB at 2514 GHz. Using a CO/sub 2/-pumped methanol far-infrared laser as a local oscillator at 2522 GHz, injected via a Martin-Puplett diplexer, the required power is /spl ap/5 mW for optimum pumping and can be reduced to less than 3 mW with a 15% increase in receiver noise. Although demonstrated as a simple submillimeter-wave mixer, the all-GaAs membrane structure that has been developed is suited to a wide variety of low-loss high-frequency radio-frequency circuits.

Large- and small-signal IMD behavior of microwave power amplifiers

Abstract: In this paper, large-signal intermodulation distortion (IMD) sweet spots in microwave power amplifiers are studied and predicted using a new mathematical basis. The variations in the IMD versus drive pattern with active bias point and the terminating matching networks are investigated. This nonlinear distortion model enabled the design of power amplifiers specially tailored to present a desired IMD versus drive-level pattern. For practical validation purposes, a MESFET case study and an illustrative application example are presented.

Characterization of spectral regrowth in microwave amplifiers based on the nonlinear transformation of a complex Gaussian process

Abstract: A statistical technique is presented for the characterization of spectral regrowth at the output of a nonlinear amplifier driven by a digitally modulated carrier in a digital radio system. The technique yields an analytical expression for the autocorrelation function of the output signal as a function of the statistics of the quadrature input signal transformed by a behavioral model of the amplifier. The amplifier model, a baseband equivalent representation, is derived from a complex radio-frequency envelope model, which itself is developed from readily available measured or simulated amplitude modulation-amplitude modulation and amplitude modulation-phase modulation data. The technique is used in evaluating the spectral regrowth for a CDMA signal.

High frequency inductive lamp and power oscillator

Abstract: An oscillator includes an amplifier having an input and an output, a feedback network connected between the input of the amplifier and the output of the amplifier, the feedback network being configured to provide suitable positive feedback from the output of the amplifier to the input of the amplifier to initiate and sustain an oscillating condition, and a tuning circuit connected to the input of the amplifier, wherein the tuning circuit is continuously variable and consists of solid state electrical components with no mechanically adjustable devices including a pair of diodes connected to each other at their respective cathodes with a control voltage connected at the junction of the diodes. Another oscillator includes an amplifier having an input and an output, a feedback network connected between the input of the amplifier and the output of the amplifier, the feedback network being configured to provide suitable positive feedback from the output of the amplifier to the input of the amplifier to initiate and sustain an oscillating condition, and transmission lines connected to the input of the amplifier with an input pad and a perpendicular transmission line extending from the input pad and forming a leg of a resonant “T”, and wherein the feedback network is coupled to the leg of the resonant “T”.

A 120-W X-band spatially combined solid-state amplifier

Abstract: In this paper, we present new results in the development of a broad-band spatial power-combining system implemented in a standard X-band waveguide environment. Using 24 off-the-shelf GaAs monolithic-microwave integrated-circuit (MMIC) power amplifiers integrated with tapered-slot antenna arrays, the new combining circuit produced up to 126-W maximum power output with a gain variation of /spl plusmn/1.9 dB within the band of interest (8-11 GHz). This hybrid circuit combiner is transparent to the device technology, and also provides an excellent heat-sinking capacity, sustaining as much as 415 W of dc power consumed by the MMIC amplifiers. The modular architecture allows easy maintenance, variable output power level, and modular assembly. Results on graceful degradation are also presented, showing superb tolerance to device failure.

Adaptive linearization of power amplifiers

Abstract: A method and apparatus adaptively compensates for nonlinearities of a power amplifier by measuring a distortion characteristic across the power amplifier during amplification of a distortion detection signal The distortion detection signal has a well-defined input power versus time relationship, such as ramp-up signal or ramp-down signal Due to this well-defined relationship, the distortion characteristic can be calculated as a function of the input power level This calculated function is then utilized to update a predistortion lookup table

Characterization of Spectral Regrowth in Microwave Amplifiers Based on the Nonlinear Transformation of a

Abstract: A statistical technique is presented for the character- ization of spectral regrowth at the output of a nonlinear amplifier driven by a digitally modulated carrier in a digital radio system. The technique yields an analytical expression for the autocorrela- tion function of the output signal as a function of the statistics of the quadrature input signal transformed by a behavioral model of the amplifier. The amplifier model, a baseband equivalent rep- resentation, is derived from a complex radio-frequency envelope model, which itself is developed from readily available measured or simulated amplitude modulation-amplitude modulation and amplitude modulation-phase modulation data. The technique is used in evaluating the spectral regrowth for a CDMA signal.

Feedforward Linear Power Amplifiers

Abstract: Radio System Introduction. Linearity and Signal Description. Power Amplifier Operation. System Design. Linearization Techniques. Feedforward Analysis. Feedforward Components. Index.

High efficiency flip-chip monolithic microwave integrated circuit power amplifier

Abstract: A coplanar waveguide structure for use in constructing a monolithic microwave integrated circuit high power amplifier The coplanar waveguide structure is a coplanar transmission line segment having more than two ground plane electrodes and a plurality of signal/dc current carrying electrodes The current carrying electrodes are each separated from an adjacent ground plane electrode by a gap The coplanar waveguide structure forms a shunt inductor for the monolithic microwave integrated circuit high power amplifier The electrodes are shorted at one end to form the shunt inductor A center ground plane electrode is preferably at least twice the width of the signal carrying electrode The gaps between the signal carrying electrode and the ground electrodes are preferably at least one half the width of the signal carrying electrode to minimize current crowding

Semiconductor memory device allowing high-speed operation of internal data buses

Abstract: A current mirror-type load circuit is provided for a global data line pair. A read gate amplifier used as a block select gate for each of the local data line pairs. A read gate amplifier includes a MOS transistor having its gate connected to a corresponding local data line. A data write driver writes the logic-inverted data of the write data upon equalization after the data write operation. A high-speed access becomes possible by reducing the time required for reading of data and by reducing the write recovery time.

Digital sliding pole fast-restore for an electrocardiograph display

Abstract: A method and apparatus for monitoring an electrocardiograph waveform, and for returning an electrocardiograph trace to the middle of a display, such as a chart recorder strip, is disclosed. The monitoring circuit includes an amplifier and a switch for switching the frequency response curve of the monitoring circuit. In a first position, the switch causes the monitoring circuit to have a slow frequency response curve, which allows for accurate monitoring of ECG waveforms. In a second position, the switch causes the monitoring circuit to have a fast frequency response curve, which allows the amplifier of the monitoring circuit to quickly be brought out of saturation. The amplifier of the monitoring circuit becomes saturated when a defibrillation or pace pulse has been applied to a patient who is being monitored. The switch is controlled by a pulse waveform control signal that is provided by a microprocessor. By varying the duty cycle of the control signal, the frequency response curve of the monitoring circuit can be shifted. By changing the duty cycle of the pulse waveform in incremental steps, certain problems can be avoided, such as erroneous QRS detect marks that are otherwise produced. The incremental steps in which the duty cycle of the pulse waveform is changed may be predetermined, or they may be adjusted according to feedback from the amplifier.

Direct digital synthesis of precise, stable angle modulated RF signal

Abstract: An RF modulator that allows precise, stable phase shifts to be obtained. The modulator uses a PLL structure including an auxiliary feedforward path including an adaptive gain amplifier (411) used to inject a modulation signal into the PLL at a point past a loop filter (403). A phase demodulator (419) recovers from the output of the PLL phase information which is compared in a comparator (417) to the phase information of the modulation signal. A resulting error signal is used to control the gain of the adaptive gain amplifier (411). The modulator compensates for variability of the VCO (405) and other components of the PLL.

A monolithic transformer coupled 5-W silicon power amplifier with 59% PAE at 0.9 GHz

Abstract: This paper presents the circuit design and application of a monolithically integrated silicon radio-frequency power amplifier for 0.8-1 GHz. The chip is fabricated in a 25-GHz-f/sub T/ silicon bipolar production technology (Siemens B6HF). A maximum output power of 5 W and maximum efficiency of 59% is achieved. The chip is operating from 2.5 to 4.5 V. The linear gain is 36 dB. The balanced two-stage circuit design is based fundamentally on three on-chip transformers. The driver stage and the output stage are connected in common-emitter configuration. The input signal can be applied balanced or single-ended if one input terminal is grounded. One transformer at the input acts as balun as well as input matching network. Two transformers acts as interstage matching network.

DRAM sense amplifier for low voltages

Abstract: Structures and methods for improving sense amplifier operation are provided. A first embodiment includes a sense amplifier having a pair of cross-coupled inverters. Each inverter includes a transistor of a first conductivity type and a pair of transistors of a second conductivity type which are coupled at a drain region and are coupled at a source region. The drain region for the pair of transistors is coupled to a drain region of the transistor of the first conductivity type. A pair of input transmission lines are included where each one of the pair of input transmission lines is coupled to a gate of a first one of the pair of transistors in each inverter. A pair of output transmission lines is included where each one of the pair of output transmission lines is coupled to the drain region of the pair of transistors and the drain region of the transistor of the first conductivity type in each inverter. High performance, wide bandwidth or very fast CMOS amplifiers are possible using the new circuit topology of the present invention. The new modified sense amplifier for low voltage DRAMs is as much as 100 times faster than a conventional voltage sense amplifier when low power supply voltages, e.g. Vdd less than 1.0 Volts, are utilized. In the novel sense amplifier, the bit line capacitance is separated from the output nodes of the sense amplifier.

Field emitter arrays for plasma and microwave source applications

Abstract: Field emitter arrays (FEAs) stand to strongly impact device performance when physical size, weight, power consumption, beam current, and/or high pulse repetition frequencies are an issue. FEAs are capable of instant ON/OFF performance, high brightness, high current density, large transconductance to capacitance ratio, and low voltage operation characteristics. Advanced microwave power tubes, and in particular, inductive output amplifiers, are by far the most technically challenging use to date. Other important uses include, e.g., electron sources for micropropulsion systems–Hall thrusters–and tethers for satellites, and (the most widely pursued application) field emission displays. The characteristics of field emitters that make them attractive to such applications shall be surveyed. A thorough analytical model of a field emitter array, beginning with a review of the nature of field emission and continuing with an analytical model of a single emitter and the operation of an array of emitters, shall be presented. In particular, attention shall be directed towards those features of FEAs that render them attractive as cold cathode candidates for electron beam generation. Tip characteristics, such as emission distribution, and array operation, such as space charge effects, will be analyzed in the context of the model. Finally, restricting attention to microwave applications, the performance of a tapered-helix inductive output amplifier to highlight the advantages of high frequency emission gating of the electron beam in a power tube shall be investigated.

Integrated-antenna push-pull power amplifiers

Abstract: In this paper, the integrated-antenna concept is applied to push-pull power amplifiers (PAs). In this approach, the antenna serves as an out-of-phase power combiner and tuned load for higher harmonics. This new architecture effectively has a near-zero loss output hybrid, and results in a high-efficiency PA. The first example is a narrow-band push-pull amplifier integrated with a dual-feed patch antenna. At an operating frequency of 2.5 GHz, a maximum measured power-added efficiency (PAE) of 55% is achieved. The second example is a broadband push-pull amplifier integrated with a dual-feed slot antenna amplifier operating at 2.46 GHz which has a peak PAE of 63%, and PAE better than 55% in an 8% bandwidth. Additionally, 48% PAE is achieved with code-division multiple-access modulation and adjacent-channel power ratio better than -42 dBe at a 1.25-MHz offset.

A power re-use technique for improved efficiency of outphasing microwave power amplifiers

Abstract: An improved power re-use technique is introduced for application to outphased microwave power amplifiers. The technique allows a significant portion of the wasted out-of-phase components of the signal to be returned to the power supply, resulting in substantial improvements in overall power-amplifier efficiency. A peak re-use RF-to-DC efficiency of 63% was obtained at 1.96 GHz.