Scattering matrix approach for the design of microwave filters

A synthesis procedure, based on a distributed parameter model, for the design of microwave filters is presented in this paper. The frequency response of the filter is described in terms of the characteristic polynomial T₂₁=S₁₁/S₂₁ where S₁₁ and S₂₁ are the scattering parameters of the filter. Starting from the desired polynomial T₂₁, the design scheme directly yields the scattering parameters of the various junctions, which can be realized by any kind of discontinuity. The capability of synthesizing an arbitrary frequency response allows one to introduce the concept of a “predistorted” characteristic polynomial in order to compensate for the degradations caused by multimodal interactions, frequency dispersion, etc. Comparison with measured data of a Chebyshev-like eight-pole E-plane filter confirms the validity of the method also in the presence of losses     

Anechoic chamber evaluation using the matrix pencil method

A new method for evaluation of an anechoic chamber using the matrix pencil method is presented. A signal measured between two antennas placed in an anechoic chamber is sliced into small frequency intervals and is processed using the matrix pencil method. In each interval, the measured signal is decomposed into its propagating-wave components, which correspond to a direct propagation between two antennas and reflected propagating waves from absorbing walls. The ratio of amplitudes of the reflected wave components with respect to the direct path propagation gives a new measure of quality factor for an anechoic chamber     

A Ka-Band CMOS Wilkinson Power Divider Using Synthetic Quasi-TEM Transmission Lines

This work presents a Ka-band two-way 3 dB Wilkinson power divider using synthetic quasi-transverse electromagnetic (TEM) transmission lines (TLs). The synthetic quasi-TEM TL, also called complementary-conducting-strip TL (CCS TL), is theoretically analyzed. The equivalent TL model, whose production is based on the extracted results, is applied to the power divider design. The prototype is fabricated by the standard 0.18 mum 1P6M CMOS technology, showing the circuit size of 210.0 mumtimes390.0 mum without contact pads. The measurement results, which match the 50 Omega system, reveal perfect agreements with those of the simulations. The comparison reveals the following characteristics. The divider exhibits an equal power-split with the insertion losses (S₂₁ and S₃₁) of 3.65 dB. The return losses (S₁₁, S₂₂ and S₃₃) of the prototype are higher than 10.0 dB from 30.0 to 40.0 GHz.     

Channel coding and decoding in a relay system operated with physical-layer network coding

This paper investigates link-by-link channel-coded PNC (physical layer network coding), in which a critical process at the relay is to transform the superimposed channel-coded packets received from the two end nodes (plus noise), Y₃ = X₁+ X₂+W₃, to the network-coded combination of the source packets, S₁ oplus S₂. This is in contrast to the traditional multiple-access problem, in which the goal is to obtain both S₁ and S₂ explicitly at the relay node. Trying to obtain S₁ and S₂ explicitly is an overkill if we are only interested in S1oplusS₂. In this paper, we refer to the transformation Y₃ rarr S₁ oplus S₂ as the channel-decoding- network-coding process (CNC) in that it involves both channel decoding and network coding operations. This paper shows that if we adopt the repeat accumulate (RA) channel code at the two end nodes, then there is a compatible decoder at the relay that can perform the transformation Y₃ rarr S₁oplusS₂ efficiently. Specifically, we redesign the belief propagation decoding algorithm of the RA code for traditional point-to-point channel to suit the need of the PNC multiple-access channel. Simulation results show that our new scheme outperforms the previously proposed schemes significantly in terms of BER without added complexity.     

Invariance of S21/S12 and K-factor underparallel operation of linear two-port devices

Based on a generalized circuit model for parallel-operated amplifiers with linear two-port devices, it has been proved that the S-parameter ratio S₂₁/S₁₂ and hence MSG (maximum stable gain) are invariant as long as the devices have an identical value of S₂₁/S₁₂ and the input and output networks are reciprocal. The invariance of K factor has been shown to hold for two cases: (i) devices are identical and input/output networks are lossless and symmetric with respect to each device, and (ii) identical admittances are added to the networks of case (i) so as to connect every device port with each other. Thus at least in these two cases, MAG (maximum available gain) and U (unilateral gain) are invariant as well as MSG under parallel operation of linear two-port devices. The invariance of S₂₁/S₁₂ and hence MSG applies to a variety of parallel-operated amplifiers such as distributed amplifiers and linear power amplifiers     

Electrical characterization of ball grid array packages fromS-parameter measurements below 500 MHz

Ball grid array (BGA) packages have been characterized from one port S-parameter measurements by shorting and opening the connection on the ball side of BGA packages. Transmission line parameters (resistance, inductance and capacitance) using the Γ equivalent circuit model are extracted from the measured S₁₁ parameter. Extracted resistances are strongly dependent on frequency, but extracted inductances and capacitances are nearly constant up to 500 MHz. Extracted capacitances are well matched to those measured from an LCR meter and calculated from a three-dimensional (3-D) simulator, Capacitance in a transmission line plays an important role in electrical performance for packages so that we may model a transmission line as a single capacitor. Extracted capacitances using the single capacitor model also well represent the measured S₁₁. These results suggest that the single capacitor model can be efficiently used for the transmission line model in BGA packages up to 500 MHz     

Beam-cavity interaction circuit at W-band

In this paper, we describe the design, fabrication, and bench study of a millimeter-wave cavity employed as a relativistic klystron output structure. The oxygen-free electronic-grade copper cavity was prepared by electro-discharge machining and diffusion bonding, and cleaned and tuned to 91.4 GHz. Measured cavity characteristics are presented and compared with theory, including quality factor Q, coupling parameter β, scattering matrix S₁₁, and axial electric field profile E_z. This paper provides the basis for an understanding of the cavity as a transfer structure     

Design of active phase shifters based on multichannelheterojunction field effect transistors (MCHFET's)

Design criteria of active phase shifters based on GaAs/AlGaAs multichannel (MC) HFET in the frequency range 4-60 GHz are presented. The phase characteristics of MCHFET devices were studied using the computer aided design program TOUCHSTONE. The dependence of transmission phase on various intrinsic elements in the equivalent circuit model as a function of control gate bias was also studied. There are limited gate bias ranges which correspond to the active regions of the two conducting wells for which a quasi-linear continuous phase shift for analog applications was achieved. Continuously varying the gate bias from V_gs=-1.9 V to V_gs=-0.6 V results in a quasilinear phase shift of 10°, 15°, 21°, and 29° at f=12, 20, 30, and 60 GHz, respectively. Similarly, varying the gate bias from V_gs =-0.4 V to V_gs=0.7 V a quasi-linear phase shift of 21°, 26°, 27°, and 23° at f=12, 20, 30, and 60 GHz, respectively, was achieved. The gain variation was less than 3 dB in these bias regions. With digital applications in mind, a maximum differential phase shift of around 50° was obtained by switching the gate bias discretely. The transmission phase of single gate MCHFET mostly depends on variation of gate source capacitance with gate bias rather than on other intrinsic elements. The dependence of phase shift on various geometrical and structural parameters is also presented. To test the practicality of the device, other scattering parameters (e.g., S₁₁, S₂₂, S₁₂) and the noise figure (NF) were finally studied     

A microwave oscillation loop for dielectric constant measurement

We designed and analyzed a microwave oscillation loop formed by a dielectric loaded cavity, amplifiers and transmission lines for the dielectric constant measurement of samples at both room and very high temperature. An oscillation condition for an arbitrary loop is derived in S-parameter notation, by which the commonly used oscillation condition in loop phase and gain notation is proved to be valid only in the special case when either S₁₁=S₂₁=0 or S₂₂ =S₁₂=0. Based on the S-parameter oscillation condition, a theoretical model is established and verified with a discrepancy of less than 0.041% between the calculated and the measured oscillation frequencies. With this model, the loop characteristics are investigated. From the measured loop oscillation frequency, the cavity resonant frequency, and thereby the dielectric constant of the sample in the cavity, can be predicted. Based on this analysis, an active dielectrometer is constructed with resultant errors of less than 4% for ϵ'<20 and less than 11% for ϵ'<80. This dielectrometer requires no tuning and no external microwave power source. Moreover, a high power (>100 W) oscillation loop for the dielectric constant measurement of a microwave heated sample (1000°C) is developed     

收扩喷管设计对双S形二元排气系统气动与红外特征的影响

为了研究双S形二元收扩排气系统的气动与红外辐射特性,基于一个基准加力型轴对称排气系统,设计了三种带正尾向全遮挡收扩喷管的双S形二元排气系统模型,通过数值模拟研究了喉道与出口的中心线偏径比差,(S₈?S₉)/D=0.26~0.3,和喉道至出口的宽度扩张比,(W₉?W₈)/D=0.1~0.36,对排气系统气动与红外特征的影响。结果表明:所设计的三种双S形二元收扩排气系统,相比基准轴对称排气系统,在尾向0°~15°角域内红外辐射强度平均降幅在73.4%以上,在上方、下方和侧方90°探测角降幅在60.3%以上,红外辐射强度降幅随(S₈?S₉)/D的减小而上升,随(W₉?W₈)/D的增大而上升,且对(S₈?S₉)/D的敏感较高。三种排气系统的推力系数随(S₈?S₉)/D与(W₉?W₈)/D的降低而上升。     

First demonstration of monolithic InP-based HBT amplifier with PNPactive load

An InP-based integrated HBT amplifier with PNP active load was demonstrated for the first time using complementary HBT technology (CRBT). Selective molecular beam epitaxy (MBE) regrowth was employed and a merged processing technology was developed for the monolithic integration of InP-based NPN and PNP HBTs on the same chip. The availability of PNP devices allowed design of high gain amplifiers with low power supply voltage. The measured amplifier with PNP HBT active load achieved a voltage gain of 100 with a power supply (V_CC) of 1.5 V. The corresponding voltage swing was 0.9 V to 0.2 V. The amplifier also demonstrated S₂₁ of 7.8 dB with an associated S₁₁ and S₂₂ of -9.5 dB and -8.1 dB, respectively, at 10 GHz     

Nested input-constrained codes

An input-constrained channel, or simply a constraint, is a set S of words that is generated by a finite labeled directed graph. An encoder for S maps, in a lossless manner, sequences of unconstrained input blocks into sequences of channel blocks, the latter sequences being words of S. In most applications, the encoders are finite-state machines and, thus, presented by state diagrams. In the special case where the state diagram of the encoder is (output) deterministic, only the current encoder state and the current channel block are needed for the decoding of the current input block. In this work, the problem of designing coding schemes that can serve two constraints simultaneously is considered. Specifically, given two constraints S₁ and S ₂ such that S₁⊆S₂ and two described rates, conditions are provided for the existence of respective deterministic finite-state encoders ε₁ and ε₂ , at the given rates, such that (the state diagram of) ε₁ is a subgraph of ε₂ Such encoders are referred to as nested encoders. The provided conditions are also constructive in that they imply an algorithm for finding such encoders when they exist. The nesting structure allows to decode ε₁ while using the decoder of ε₂. Developments in optical recording suggest a potential application that can take a significant advantage of nested encoders     

基于耦合腔的太赫兹垂直传输结构

提出了一种工作在110 GHz的耦合腔垂直传输结构。在垂直金属腔的两端对称地装配两个模式变换单元,作为波导的两个激励端口。模式变换单元在50 μm厚度石英基片上实现,该基片采用通孔结构和双面镀金工艺。因此,该垂直传输结构在太赫兹频段具有较低的插入损耗。仿真结果与测试结果拟合良好,模式变换单元的 S₂₁仿真结果为?0.7 dB,测试结果小于?1.3 dB,在105~116 GHz带宽的反射系数低于?10 dB。     

Antenna-Pattern Measurement Using Spectrum Analyzer for Systems with Frequency Translation [Measurements Corner]

Pattern measurements using a network analyzer are typically based on measuring the transmission coefficient, S₂₁. When the transmitting and receiving frequencies are different, it is not possible to directly measure the antenna pattern using a network analyzer. In this paper, an antenna-pattern measurement system using a spectrum analyzer, designed to measure the radiation pattern of an antenna with a microwave sampling beamformer (MSBF) structure, is presented. A synthesized oscillator was used as the transmitter in the measurement setup. The instruments were controlled through GPIB by a program specifically designed for the system. High-quality pattern measurements were obtained for several antenna types. The measurement results were verified using HFSS simulations.     

A 60-dB gain, 55-dB dynamic range, 10-Gb/s broad-band SiGe HBTlimiting amplifier

A limiting amplifier IC implemented in a silicon-germanium (SiGe) heterojunction bipolar transistor technology for low-cost 10-Gb/s applications is described. The IC employs 20 dB gain limiting cells, input overload protection, split analog-digital grounds, and on-chip isolation interface with transmission lines. A gain enhancement technique has been developed for a parallel-feedback limiting cell. The limiting amplifier sensitivity is less than 3.5 mV_pp at BER=10^-9 with 2-V_pp maximum input (55-dB dynamic range). The total gain is over 60 dB, and S₂₁ bandwidth exceeds 15 GHz at 10-mV_pp input. Parameters S₁₁ and S₂₂ are better than -10 dB in the 10-GHz frequency range. The AM to PM conversion is less than 5 ps across input dynamic range. The output differential voltage can be set from 0.2 to 2 V_pp with IC power dissipation from 250 mW to 1.1 W. The chip area is 1.2×2.6 mm². A 10-Gb/s optical receiver, built with the packaged limiting amplifier, demonstrated -19.6-dBm sensitivity. The IC can be used in 10-Gb/s fiber-optic receivers requiring high sensitivity and wide input dynamic range     

Fabrication and Characteristics of 40-Gb/s Traveling-Wave Electroabsorption Modulator-Integrated DFB Laser Modules

We have developed 40-Gb/s traveling-wave electroabsorption-modulator-integrated distributed feedback laser (TW-EML) modules using several advanced technologies. First, we have adopted a selective area growth (SAG) method in the fabrication of the 40-Gb/s EML device to provide active layers for the laser and the electroabsorption modulators (EAMs) simultaneously. The fabricated device shows that the measured 3-dB bandwidth of electrical-to-optical (E/O) response reaches about 45 GHz and the return loss (S₁₁) is kept below -10 dB up to 50 GHz. For the module design of the device, we mainly considered electrical and optical factors. The measured S₁₁ of the fabricated 40 Gb/s TW-EML module is below -10 dB up to about 30 GHz and the 3-dB bandwidth of the E/O response reaches over 35 GHz. We also have developed two types of coplanar waveguide (CPW) for the application of the driver amplifier integrated 40 Gb/s TW-EML module, which is a system-on-package (SoP) composed of an EML device and a driver amplifier device in a module. The measured S₁₁ of the two-step-bent CPW is below -10 dB up to 35 GHz and the measured S₁₁ of the parallel type CPW is below -10 dB up to 39 GHz.     

0.18 μm 21-27 GHz CMOS UWB LNA with 9.3 ± 1.3 dB gain and 103.9 ± 8.1 ps group delay

A 21-27 GHz CMOS ultra-wideband low-noise amplifier (UWB LNA) with state-of-the-art phase linearity property (group delay variation is only ± 8.1 ps across the whole band) is reported for the first time. To achieve high and flat gain (S₂₁) and small group delay variation at the same time, the inductive series peaking technique was adopted in the output of each stage for bandwidth enhancement. The LNA dissipated 27 mW power and achieved input return loss (S₁₁) of 213 to 220.1 dB, output return loss (S₂₂) of 28.2 to 230.2 dB, flat S21 of 9.3 ± 1.3 dB, reverse isolation (S₁₂) of 252.7 to 273.3 dB, and noise figure of 4.9?6.1 dB over the 21-27 GHz band of interest. The measured 1 dB compression point (P_1dB) and input third-order intermodulation point (IIP3) were 214 and 24 dBm, respectively, at 24 GHz.     

3–10-GHz Ultra-Wideband Low-Noise Amplifier Utilizing Miller Effect and Inductive Shunt–Shunt Feedback Technique

In this paper, we demonstrate an SiGe HBT ultra-wideband (UWB) low-noise amplifier (LNA), achieved by a newly proposed methodology, which takes advantage of the Miller effect for UWB input impedance matching and the inductive shunt-shunt feedback technique for bandwidth extension by pole-zero cancellation. The SiGe UWB LNA dissipates 25.8-mW power and achieves S₁₁ below -10 dB for frequencies from 3 to 14 GHz (except for a small range from 10 to 11 GHz, which is below -9 dB), flat S₂₁ of 24.6 plusmn 1.5 dB for frequencies from 3 to 11.6 GHz, noise figure of 2.5 and 5.8 dB at 3 and 10 GHz, respectively, and good phase linearity property (group-delay variation is only plusmn28 ps across the entire band). The measured 1-dB compression point (P₁ dB) and input third-order intermodulation point are -25.5 and -17 dBm, respectively, at 5.4 GHz.     

Comments on “A deterministic approach for designingconditionally stable amplifiers”

For original paper see M.L. Edwards et al., ibid., vol.43, no.7, pp.1567-75 (July 1995). In the above paper, the authors presented a careful analysis of single-sided matched conditionally stable amplifiers. In particular, they determined a maximum single-sided matched gain G_msm which is reached for passive jointly stable source (load) terminations G_msm=2 kG_ms where k is the Rollett's stability factor and G_ms=|S₂₁/S₁₂| is the maximum stable gain of device. However, at least some of the results presented in the above paper can be found in other literature. In this paper, I would like to outline the formerly published papers treating conditionally stable amplifiers in terms of the scattering parameters. A reply by the original authors is included     

Full-wave analysis of choking characteristics of sleeve balun oncoaxial cables

An optimal design for a sleeve balun with maximum choking on a coaxial cable is determined using a full-wave body of revolution finite difference time domain method with perfectly matched layer boundary conditions. An analysis of the sensitivity of choke length L and outer diameter R₂ on choking effectiveness was carried out. A balun with L=77.5 mm (0.232λ₀) and R₂=8 mm on a cable with R₁=2 mm (R₂/R₁=4) results in an S₂₁ of -20 dB at 900 MHz and -15.5 dB at 2730 MHz. The isolation of the balun at 900 MHz is quickly degraded as the R₂ /R₁ ratio is reduced below 2. Increasing R₂/R₁ to 8, results in a reduction of optimum balun length L to approximately 0.215λ₀, approximately 14% shorter than the typical recommended length for an 'ideal' quarter-wave balun