Output Reflection Coefficients Research Articles

A Large-Swing Transformer-Boosted Serial Link Transmitter With $>{\rm V}_{\rm DD}$ Swing

The design and analysis of a large-swing transformer-boosted serial link transmitter is described. Transformer boosting is used to produce a signal swing that is not constrained by the supply voltage and enables a true pre-emphasis transmitter with a differential output swing greater than the supply. The boosted signal is separated from the driver through series inductors and therefore does not stress the transistor voltage tolerance. Several design tradeoffs between the amounts of boosting, power, and output matching are examined in both analysis and simulation. Distributed boosting is employed to relax the tradeoff between the amount of boosting and output matching degradation. Implemented in a 0.13-mum CMOS technology, the prototype chip produces an 8-Gb/s PRBS 2 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">31</sup> -1 data pattern and achieves a 1.42 V <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">pp</sub> differential output swing while drawing 137 mA current from a 1.2-V supply. The measured output reflection coefficient is better than -10dB up to 4 GHz

Adjoint network method applied to the performance sensitivities of microwave amplifiers

This work focuses on the performance sensitivities of microwave amplifiers using the “adjoint network and adjoint variable” method, via “wave” approaches, which includes sensitivities of the transducer power gain, noise figure, and magnitudes and phases of the input and output reflection coefficients. The method can be extended to sensitivities of the other performance measure functions. The adjoint-variable methods for design-sensitivity analysis offer computational speed and accuracy. They can be used for efficiency-based gradient optimization, in tolerance and yield analyses. In this work, an arbitrarily configured microwave amplifier is considered: firstly, each element in the network is modeled by the scattering matrix formulation, then the topology of the network is taken into account using the connection scattering-matrix formulation. The wave approach is utilized in the evaluation of all the performance-measurement functions, then sensitivity invariants are formulated using Tellegen's theorem. Performance sensitivities of the T- and Π-types of distributed-parameter amplifiers are considered as a worked example. The numerical results of T- and Π-type amplifiers for the design targets of noise figure Freq = 0.46 dB ⇔ 1,12 and Vireq = 1, GTreq = 12 dB ⇔ 15.86 in the frequency range 2–11 GHz are given in comparison to each other. Furthermore, analytical methods of the “gain factorisation” and “chain sensitivity parameter” are applied to the gain and noise sensitivities as well. In addition, “numerical perturbation” is applied to calculation of all the sensitivities. © 2006 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2006.

Accurate substrate modelling of RF CMOS

The losses within the substrate of an RF IC can have significant effect on performance in a mixed signal application. In order to model substrate coupling accurately, it is represented by an RC network to account for both resistive and dielectric losses at high frequency (> 1 GHz). A small-signal equivalent circuit model of an RF IC inclusive of substrate parasitic effect is analysed in terms of its y-parameters and an extraction procedure for substrate parameters has been developed. By coupling the extracted substrate parameters along with extrinsic resistances associated with gate, source and drain, a standard BSIM3 model has been extended for RF applications. The new model exhibits a significant improvement in prediction of output reflection coefficient S22 in the frequency range from 1 to 10 GHz in device mode of operation and for a low noise amplifier (LNA) at 2.4 GHz. Copyright © 2006 John Wiley & Sons, Ltd.

위성 DAB 수신을 위한 저잡음 증폭기의 설계 및 구현에 관한 연구

본 논문에서는 1,452∼l,492 MHz L-Band 대역의 위성 DAB 수신기를 위한 저잡음증폭기를 입ㆍ출력 반사계수와 전압정재파비를 개선하기 위하여 평형증폭기 형태로 설계 및 제작하였다. 저 잡음증폭기는 GaAs FET소자인 ATF-10136을 사용한 저 잡음증폭단과 MMIC 소자인 VNA-25을 사용한 이득증폭단을 하이브리드 방식으로 구성하였으며, 최적의 바이어스를 인가하기 위하여 능동 바이어스 회로를 사용하였다. 적용된 능동 바이어스 회로는 소자의 펀치오프전압(<TEX>$V_P$</TEX>)과 포화드래인 전류(<TEX>$I_{DSS}$</TEX>)의 변화에 따라 주어진 바이어스 조건을 만족시키기 위해 소스 저항과 드래인 저항의 조절이 필요없다. 즉, 능동 바이어스 회로는 요구된 드래인 전류와 전압을 공급하기 위해 게이트-소스 전압(<TEX>$V_{gs}$</TEX>)을 자동적으로 조절한다. 저잡음증폭기는 바이어스 회로와 RF 회로를 FR-4기판 위에 제작하였고, 알류미늄 기구물에 장착하였다. 제작된 저잡음증폭기는 이득 32 dB, 이득평탄도 0.2 dB, 0,95 dB 이하의 잡음지수, 입ㆍ출력 전압정재파비는 각각 1.28, 1.43이고, <TEX>$P_{1dB}$</TEX> 는 13 dBm으로 측정되었다. In this paper, a LNA(Low Noise Amplifier) has been developed, which is operating at L-band i.e., 1452∼1492 MHz for satellite DAB(Digital Audio Brcadcasting) receiver. The LNA is designed to improve input and output reflection coefficient and VSWR(Voltage Standing Wave Ratio) by balanced amplifier. The LNA consists of low noise amplification stage and gain amplification stage, which make a using of GaAs FET ATF-10136 and VNA-25 respectively, and is fabricated by hybrid method. To supply most suitable voltage and current, active bias circuit is designed Active biasing offers the advantage that variations in <TEX>$V_P$</TEX> and <TEX>$I_{DSS}$</TEX> will not necessitate a change in either the source or drain resistor value for a given bias condition. The active bias network automatically sets <TEX>$V_{gs}$</TEX> for the desired drain voltage and drain current. The LNA is fabricated on FR-4 substrate with RF circuit and bias circuit, and integrated in aluminum housing. As a reults, the characteristics of the LNA implemented more than 32 dB in gain. 0.2 dB in gain flatness. lower than 0.95 dB in noise figure, 1.28 and 1.43 each input and output VSWR, and -13 dBm in <TEX>$P_{1dB}$</TEX>.

A 23.8-GHz SOI CMOS tuned amplifier

A 23.8-GHz tuned amplifier is demonstrated in a partially scaled 0.1-/spl mu/m silicon-on-insulator CMOS technology. The fully integrated three-stage amplifier employs a common-gate, source-follower, and cascode with on-chip spiral inductors and MOS capacitors. The gain is 7.3 dB, while input and output reflection coefficients are -45 and -9.4 dB, respectively. Positive gain is exhibited beyond 26 GHz. The amplifier draws 53 mA from a 1.5-V supply. The measured on-wafer noise figure is 10 dB, while the input-referred third-order intercept point is -7.8 dBm. The results demonstrate that 0.1-/spl mu/m CMOS technology may be used for 20-GHz RF applications and suggest even higher operating frequencies and better performance for further scaled technologies.

Effect of Multi-Mode Optically Pumped Far-Infrared Laser Cavity on Spectra and Multi-Raman Interaction

Based on semi-classical density matrix theory, the spectral characteristics and multi-Raman interaction of multi-longitudinal-mode CO2-9R(30) optically pumped cavity NH3 molecules 67.2 μ m far-infrared laser were theoretically studied. And with different parameters such as input and output reflection coefficient, length of tube and so on, the rules of multi-Raman interaction and effect on longitudinal structure of 67.2 μ m far-infrared laser spectrum were also discussed theoretically.

Calculation of the power capabilities of HBT amplifiers based on a new physical HBT model

A novel model for the simulation of the microwave power capabilities of HBTs is presented. The model is based on physical analytical formulation of the terminal currents as functions of the base-emitter and base-collector voltages. It takes into account the unequal thermal distribution of temperature for multifinger HBT devices, the impact ionization, tunnelling, recombination currents, etc. From the simulation of multi-finger transistor structures it can be concluded that high thermal device resistances are detrimental for power performance, because of the unequal distribution of temperature and, hence, base current in the HBT structure. In can also be concluded that the input and output reflection coefficients are insensitive to temperature variation. Finally, it has been shown theoretically and experimentally that the breakdown voltage increases slightly with increasing operating temperature. © 1996 John Wiley & Sons, Inc.

Design of a matrix amplifier using FET‐gate‐width tapering

AbstractA MMIC matrix amplifier design based on FETs with tapered gate width is proposed. The Tschebyscheff filter theory is applied to each of the artificial transmission lines composing the matrix amplifier. The improvement of the input and output reflection coefficient and the reduction of the FET's width in comparison to a conventional matrix amplifier with equivalent performance demonstrates the effectiveness of the presented approach.

5 Gbit/s laser-driver GaAs IC

A design of a 5 Gbit/s laser-driver GaAs IC employing a novel 50 Ω impedance matched output driver is presented. Eye diagrams with good eye openings, clean waveforms and output reflection coefficients of less than –8 dB for frequencies up to 10 GHz are demonstrated over a 10–36 mA output current tuning range.

A 4 Gb/s 2-level to 2 Gsymbol/s 4-level converter GaAs IC for semiconductor optical amplifier QPSK modulators

The design of a 50 /spl Omega/ impedance matched two-to-four level converter GaAs IC for two-electrode semiconductor optical amplifier (SOA) modulators is presented. The designed IC exhibits eye diagrams with eye openings of better than 0.30 V and a spacing between adjacent output signal levels of 0.33 V for output symbol rates of up to 2 Gsymbol/s corresponding to input bit rates of up to 4 Gb/s. A novel differential super buffer output driver is applied, for which output reflection coefficients |S/sub 22/| of less than -12 dB for frequencies up to 10 GHz are obtained. A 1 Gb/s optical QPSK microwave link transmission experiment using a packaged sample of the designed IC and a two-electrode semiconductor optical amplifier phase modulator has been conducted. >

S parameters: a practical education

The course on radiofrequency amplifier design by the technique of S-parameters offered at Virginia Polytechnic Institute and State University is described with some emphasis on the associated laboratory portion of the course. The course begins with microstrip amplifier construction and the modeling of both lumped and distributed circuit elements. Attention is then given to the design of a transistor amplifier in the UHF spectrum. Biasing and parameter measurement are first considered. Matching networks are then designed and installed, followed by the measurement of several amplifier specifications. In five years of running the laboratory course there has never been a case of a student failing to end the course with a working amplifier. Typical amplifiers (900 MHz) have gains of 12 and 13 dB, input and output reflection coefficients below 0.05, third-order intercept points of 0-10 dBm (input), and noise figures near 5 dB. >

A simple method of removing receiver noise from microwave noise measurements

A simple method is introduced by which, during measurements of noise figure and gain, the output reflection coefficient of the device under test can be adjusted to some constant value without the use of a network analyser, thereby keeping the noise figure of the noise measurement system constant. This removes an important source of error in noise figure and noise parameter measurements.A circulator and tuning network (e.g. a three-stub tuner) are used, but there is no need for the circulator to be tuned for perfect circulation. In an experimental test to verify the accuracy of the method, excess noise temperatures and available gains of a two-port were measured for a wide range of values of the complex reflection coefficient of the noise source and compared against values calculated from the measured scattering parameters of the same two-port.

The Declining Drain Line Lengths Circuit--A Computer Derived Design Concept Applied to a 2 26.5-GHz Distributed Amplifier

The principle of the declining drain line lengths has emerged as a successful concept in the pursuit of improved gain flatness and bandwidth. The optimized performance parameters of an identical links gain module are compared to those of a declining drain line lengths gain module, and the advantages of one design principle over the other are discussed. In addition, the paper studies the RF voltages and currents of the circuits' GaAs MESFETs and draws some qualitative conclusions as to the causes of gain limiting when approaching nonlinear operation. Finally, experimental results of a power module based on the declining drain line lengths principle are reported. The hybrid amplifier which incorporates five active devices with 0.25-µm gates achieves a small signal gain of G = 6.1+-0.6 dB from 2-27 GHz. Measurements of its output power, reflection coefficients and noise figure are afso discussed.

Exact Simulation and Sensitivity Analysis of Multiplexing Networks

This paper presents a novel approach to the simulation and sensitivity analysis of multiplexing networks. All computations are performed efficiently utilizing the concept of forward and reverse analysis which is elegant and effective in cascaded circuit analysis. Formulas are derived for such responses as input or output reflection coefficient, common port and channel output port return losses, insertion loss, gain slope, and group delay. Exact sensitivities w.r.t. all variables of interest, including frequency, are evaluated. The fundamental assumption is that the transmission matrices for the individual components of the network and their sensitivities w.r.t. possible variables inside them are available. An explicit algorithm is provided describing the details of the computational aspects of our theory. The formulas are applied to the optimal design of practical contiguous or noncontiguous band multiplexer consisting of multicavity filters distributed along a waveguide manifold. An example of optimizing a practical 12 channel, 12-GHz contiguous band multiplexer without dummy channels, which is the state-of-the-art structure used as the output multiplexer in satellite transponders, is presented.

Scattering matrix representation for the microwave Hall effect in the depolarization regime

Microwave Hall-effect measurements have proven invaluable for determining the Hall mobility in a wide variety of both organic and inorganic materials. Since some of these materials crystallize into needle shapes, the question of depolarization effects and the measurement and interpretation of the cavity-scattering parameters describing the microwave Hall effect have yet to be addressed. It will be shown in this paper that the microwave Hall mobility can be found under any polarization conditions by direct measurement of the cavity input and output reflection coefficients, as well as the cavity transmission factor. Experimental results supporting this premise are presented. In addition, the sign of the microwave Hall mobility is shown to be a function of the degree of sample polarization.

GaAs Monolithic Low-Power Amplifiers with RC Parallel Feedback (Short Paper)

GaAs monolithic broad-band low-power-dissipated amplifiers with inductive/resistive load and RC parallel feedback circuits have been developed. An inductive load amplifier provides a gain of 8 dB, a 3-dB bandwidth of 2.5 GHz, and a noise figure of 2.7 dB at 1 GHz with less than + 1-V supply voltage and very low-power dissipation of 20 mW. A resistive load two-stage amplifier provides a gain of 15 dB and a 3-dB bandwidth of 2 GHz. Input and output reflection coefficients at 1 GHz are -13 dB and -21 dB, respectively.

Noise in Broad-Band GaAs MESFET Amplifiers with Parallel Feedback

The influence of the circuit elements of a single-ended feedback amplifier module on noise figure and gain, as well as on input and output reflection coefficients is discussed. Theoretical results are supported by tests performed on a five-stage single-ended amplifier. The unit exhibits 41.5+-0.8 dB of small-signal gain and a maximum noise figure of 4.0 dB between 2.4 and 8.0 GHz. Maximum reflection coefficients of 1.7:1 for the input and 1.5:1 for the output terminal were measured. The unit's overall circuit dimensions are 25x3.6 mm.

Direct measurement techniques of transmission line corrections for thermal noise standards

A thermal noise source consists of a matched termination and a transmission line. A method which permits a direct measurement of the correction due to the transmission line effects on the thermal noise source without any measurement of temperature, loss, and reflection distribution in the transmission line is presented. Generalised expressions for the equivalent temperature of the thermal noise source are derived, which are composed of the temperature of the matched termination, the output reflection coefficient, and the transmission corrections. It is shown that the corrections can be determined from reflection coefficients and noise outputs of the source in which the matched termination is replaced by a short. A possibility is suggested, that higher accuracy in the correction will be obtained by the new method than by conventional ones. A 10-GHz noise source is tested by the method.

Wideband Amplifier Design Using Major Multiloop Feedback Techniques

Multiloop feedback has heretofore been ignored as a means of obtaining shaped gain amplifiers. In this paper, a theoretical basis is developed for using dual major loop feedback amplifiers to obtain shaped power gain with input and output reflection coefficient constraints. From the theoretical results, practical design procedures can easily be developed and one such procedure is discussed. The aim of this study was an alternative to the “brute force” termination technique of realizing input and output impedance matches. The development is otherwise unique in that it uses no hybrid transformers for beta circuit coupling or for realization of the reflection coefficient constraints.

A back-matched delay-line clipping technique for use with fast amplifiers

A modified delay-line clipping amplifier technique which overcomes the drift and low-frequency noise problems of conventional dc-coupled pulse amplifiers is proposed. This technique results in an amplifier system with low output reflection coefficient and excellent overload recovery characteristics.