1,721,166 research outputs found
Algorithmic Test of the Unconditional Stability of Three-Port Networks
No full textA geometrical test for the unconditional stability of three-port networks is presented. The derivation is presented in full detail, starting from the concept of input mapping region as an indicator of unconditional stability. A novel set of (equivalent) parameters is then defined, which can serve to rapidly check the unconditional stability of a three-port network under test. Although the derivation is rather lengthy, the final part of the contribution shows that the practical application of the test is actually straightforward
Improved microwave attenuator topology minimizing the number of control voltages
No full textThis letter presents an improved circuit topology to minimize the number of external control voltages that are required to set the state of an N-bit microwave digital attenuator. An alternative method to connect the control signal is proposed. Typically, the control signal is connected to the gate terminal of the field effect transistor while the source terminal is DC grounded. Here, the control signal is applied to the source terminal of the field effect transistor while the gate is connected to a fixed reference voltage. In this way, only one control voltage is necessary to set the state of single attenuator cell vs two control voltages required in the typical case. The proposed method becomes particularly beneficial as the number of bits increases (ie, >4). The topology has been validated through design, realization, and testing of a 5-bit Monolithic Microwave Integrated Circuit (MMIC) attenuator operating over the full C-band (4-8 GHz)
A novel design methodology for simultaneously matched LNAs based on noise measure
No full textThis contribution presents a novel narrow-band design methodology for low-noise amplifiers which is based on the use of the noise measure and of the reactive interstage networks. The most interesting result is the chance of obtaining a simultaneous matching condition both at the input and at the output ports of the amplifier without sacrifying the noise factor, which is also optimized. Moreover, as a test vehicle of the presented procedure, the design of a K-band LNA is discussed which has been developed starting from the narrow-band approach. © 2009 EuMA
On the Optimum Noise-Gain Locus of Two-Ports
No full textA novel result is presented concerning the locus, on the source reflection coefficient plane, of the optimum tradeoff between noise factor and available gain. Although this locus has been discussed and exploited in previous contributions, here, it is shown in a simple manner that it must be an arc of a circumference with center Ctc and radius ρtc (tangency circle). A handy transformation (a reversible, conformal one) of two-port networks is adopted to study the problem in a simplified, yet general, representation. Properties of the tangency circle are observed in this 'noise-centered' representation which are preserved under the conformal transformation, thus providing two equivalent, closed-form approaches to computing Ctc and ρtc. The second method presented lends itself to being easily implemented in commercial circuit simulators, thus serving as the basis of a simple design method for single-stage low-noise amplifiers
Constant mismatch circles and application to low noise microwave amplifier design
No full textConstant input and output mismatch circles in the output load plane are introduced as the basis for low-noise amplifier design methodology. Optimum tradeoff between input and output matching levels results as the application of a design chart providing, at the same time, the corresponding stage transducer gain. The role of degenerative series feedback is studied and systematically embedded in the design procedure, thus providing a direct way to evaluate its optimum leve
A Generalized Unterminating Technique for Characterizing Reciprocal Three-Port Networks
No full textA novel technique for characterizing reciprocal three-port networks is proposed. The approach is an extension of the conventional unterminating method for characterizing two-port networks: on the one hand, the latter extracts the parameters of a (reciprocal) two-port network from one-port measurements, and on the other hand, the presented generalization extracts the parameters of a (reciprocal) three-port network from two-port measurements. The technique is believed of interest particularly for those which occasionally need to perform three-port vector-corrected measurements of three-port test-bench components such as baluns and directional couplers but do not have access to multiport equipment and software
Ka-band High-linearity and Low-noise Gallium Nitride MMIC Amplifiers for Spaceborne Telecommunications
Full text linkGallium Nitride is becoming an interesting solution for low-noise applications in the lower part of the millimetre-wave spectrum and is gaining increasing attention in the space community for microwave receiver functionalities. Lately, its maturity level has increased and its performance in terms of noise figure and operating frequency is reaching other advanced III-V technologies such as Gallium Arsenide and Indium Phoshpide. Moreover, Gallium Nitride features higher power handling capability in comparison to the previously mentioned III-V technologies. In this context, we have designed and characterized two demonstrator circuits of critical microwave receiver functionalities: a Low-Noise Amplifier and a Low-Distortion Amplifier operating at Ka-band. It is shown that GaN circuits compare well in terms of noise figure, gain, and operating frequency with respect to other advanced III-V technologies, and most of all exhibit superior linearity in terms of intermodulation distortion. The designed Low-Noise Amplifier exhibits state-of-the-art 1.2 dB Noise Figure in the 27-31 GHz bandwidth thanks to a profitable combination of 60- and 100-nm gate length transistors on the same MMIC. On the other hand, the Low-Distortion Amplifier features state-of-the-art +30 dBm Output Third Order Intercept point in the same operating bandwidth while requiring only 216 mW dc power. The presented electrical performances are validated by comparing these designs to others available in open literature through figures of merit that normalize trade-offs by transistor length (therefore a fair comparison) aiming to highlight the merits of the proposed design methodologies
Modelling and design aids for millimetre-wave low-noise amplifiers
No full textSuccessful low-noise amplifier (LNA) design at millimetre-wave relies on accurate device linear noise models together with the availability of high-performance and versatile technologies. While device linear modelling is quite practical even at millimetre-wave, the same cannot be said for noise characterization and modelling. Often the latter can be reasonably performed only up to a few tenths of GHz. A complete device linear and noise modelling strategy, oriented to millimetre-wave LNA design, is provided in this contribution, relying on low-frequency noise characterization and millimetre-wave linear characterization. The effect of source degeneration, often applied in LNA design, above 100 GHz is also evaluated
A GaN Single-Chip Front End With Improved Efficiency and Power by Using Class F Approach
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