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The Voltage Conveyor (VCII) is the dual of the second generation Current Conveyor (CCII), and has received only a cursory attention in the literature, probably for lack of interesting applications. The VCII has a current buffer between Y and X terminals, and a voltage buffer between X and Z terminals. In this way, it makes it easier to sum (current) signals at the Y node, whereas CCIIs make it easier to sum (current) signals at the X node. Exploiting this difference between the two dual circuits, a very simple N-port synthesizer can be obtained using only N VCIIs. A mixed-signal Y-matrix synthesizer using VCIIs is also proposed, which is the dual of a similar one using CCIIs, and can also be used as an N-port analyzer, with an advantage with respect to the CCII-based version related to the possibility of sensing low-impedance (voltage) inputs. An inductor emulator and a lowpass / bandpass biquad filter are also simulated, showing the versatility of the VCII.

A methodology to design high-power amplifiers composed of several amplifier blocks and passive combiners/dividers is proposed.The optimum matching condition between amplifiers and combiners has been found using the mixed-mode S-parameters approach. Measurements and computer-aided design simulations have been successfully used to validate the proposed approach. © 2013 Wiley Periodicals, Inc. Microwave Opt Technol Lett 55:1500–1504, 2013; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.27600

In this article, a statistical nonlinear model of GaAs HEMT MMICs based on standard CAD library models is presented. A previously developed extraction procedure is used to determine model parameters. Extraction and CAD implementation of the model in 1–50 GHz frequency range provide validation of both the statistical model and the extraction procedure. © 2009 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 2163–2166, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24543

The paper deals with a possible use of the feed array present in a large antenna system, as a layer for measuring the antenna performance with a self-test procedure and a possible way to correct residual errors of the Antenna geometry and of the antenna distortions. Focus has been concentrated on a few key critical elements of a possible feed array metrology program. In particular, a preliminary contribution to the design and development of the feed array from one side, and the subsystem dedicated to antenna distortion monitoring and control from the other, have been chosen as the first areas of investigation. Scalability and flexibility principles and synergic approach with other coexistent technologies have been assumed of paramount importance to ensure ease of integrated operation and therefore allowing in principle increased performance and efficiency. The concept is based on the use of an existing feed array grid to measure antenna distortion with respect to the nominal configuration. Measured data are then processed to develop a multilayer strategy to control the mechanical movable devices (when existing) and to adjust the residual fine errors through a software controlled phase adjustment of the existing phase shifter The signal from the feed array is converted passing through a FPGA/ASIC level to digital data channels. The kind of those typically used for the scientific experiments. One additional channel is used for monitoring the antenna distortion status. These data are processed to define the best correction strategy, based on a software managed control system capable of operating at three different levels of the antenna system: reflector rotation layer, sub reflector rotation and translation layer (assuming the possibility of controlling a Stewart machine), phase shifter of the phased array layer. The project is at present in the design phase, a few elements necessary for a sound software design of the control subsystem have been developed at a technological demonstrator level while the ASIC board for generating the digital data stream has been fully developed. A prototype for control accurately the position of the sub-reflector up to a diameter of 5 meters (similar to the sub reflector size of a large antenna) using a Stewart mechanism is being planned. The selection strategy of the correction modes will depend on the dynamics of the phased array (i.e. the available bits of the A/D conversion). The reaction time allowed for the correction, depending on the error type and the inertia of the sub systems. Typically, the compensation can be divided among all the adjusting elements.

The paper deals with the opportunity to introduce “Not strictly TEM waves” Synthetic detection Method (NTSM), consisting in a Three Axis Digital Beam Processing (3ADBP), to enhance the performances of radio telescope and sensor systems. Current Radio Telescopes generally use the classic 3D “TEM waves” approximation Detection Method, which consists in a linear tomography process (Single or Dual axis beam forming processing) neglecting the small z component. The Synthetic FEED ARRAY three axis Sensor SYSTEM is an innovative technique using a synthetic detection of the generic “NOT strictly TEM Waves radiation coming from the Cosmo, which processes longitudinal component of Angular Momentum too. Than the simultaneous extraction from radiation of both the linear and quadratic information component, may reduce the complexity to reconstruct the Early Universe in the different requested scales. This next order approximation detection of the observed cosmologic processes, may improve the efficacy of the statistical numerical model used to elaborate the same information acquired. The present work focuses on detection of such waves at carrier frequencies in the bands ranging from LF to MMW. The work shows in further detail the new generation of on line programmable and reconfigurable Mixed Signal ASIC technology that made possible the innovative Synthetic Sensor. Furthermore the paper shows the ability of such technique to increase the Radio Telescope Array Antenna performances.

In this paper we present a methodology to calibrate and correct frequency-dependent errors in phased-array antennas with large signal bandwidth and large size. If the receivers are not narrow-band, the hypotheses of constant gain and group delay are not valid. If the frequency responses of the receivers are affected by mismatches, this will also impact directivity. Standard Amplitude and Phase Correction (APC) algorithms will not be effective in this case, and a more advanced complex FIR filtering algorithm is used. A transmitted signal is assumed to be known in order to provide a reference and estimate the optimal calibration coefficients of the FIR filters.

A nonlinear lumped-element model of MESFET and HEMT devices whose parameters are empirical functions of instantaneous voltages at the controlling internal nodes has been developed and used to design an X-band hybrid amplifier. Excellent agreement between measurements and simulated performance in small-signal and nonlinear power characteristics has been obtained. © 2001 John Wiley & Sons, Inc. Microwave Opt Technol Lett 29: 187–190, 2001.

A design criterion for the optimization of bandpass optical receivers based on lossless matching networks has been established. A minimum value for the input-equivalent noise current under the constraint of fixed transimpedance gain and an expression for detuning penalty evaluation with respect to the optimum have been found. ©1999 John Wiley & Sons, Inc. Microwave Opt Technol Lett 20: 50–53, 1999.

A model to perform time-domain simulations of noisy oscillators by means of linear time-variant systems is presented. The proposed model has been implemented in an ODE simulation software, and the obtained power spectral density has been compared to the one obtained with the SpectreRF™ circuit simulator, denoting an error lower than 2 dB. © 2002 John Wiley & Sons, Inc. Microwave Opt Technol Lett 32: 305–307, 2002.

A technique to design narrowband amplifiers by using conditionally stable transistors is presented. The proposed analytical approach allows us to design lossless matching networks, by providing power matching at one port and minimum mismatch at the other port. The use of this technique leads to high gain as well as proper stability margins. © 2001 John Wiley & Sons, Inc. Microwave Opt Technol Lett 31: 208–210, 2001.

A novel topology for an active balun which allows a differential gain 6 dB higher than a single differential pair is proposed. A transimpedance amplifier for 10 Gbit/s receivers has been designed based on this topology, which shows a transimpedance gain of 62.5 dBΩ and an input impedance of 150 Ω. © 2000 John Wiley & Sons, Inc. Microwave Opt Technol Lett 27: 257–259, 2000.

The design of a 900 MHz ceramic oscillator, delivering a power of 10 dBm, has been carried out by using the negative-resistance condition. A new procedure based on the Nyquist criterion, implemented within microwave CADs has been used to test the onset of oscillations at the desired frequency and the presence of spurious oscillation. An excellent agreement between nonlinear simulations and measurements performed on a prototype has been observed. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 1713–1717, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22528

A new methodology for yield optimization of integrated circuits is presented. We propose a dc external control scheme which performs on-line estimation of the active device model parameters and proper correction of the bias point. Design of a 2.5 Gbit/s front-end amplifier has been performed, and a strong yield improvement has been found. © 2001 John Wiley & Sons, Inc. Microwave Opt Technol Lett 31: 134–137, 2001.

4. CONCLUSION wx The reflectivity properties of a simulated simpler LTBC 8, 9 wx and NTBC 5 were studied for a typical ground-based TDP problem. For a fixed propagation step size, the LTBC demon- strated a minimum of reflectivity with respect to the trans- verse step size. This property allows a larger transverse step size when the LTBC is used in comparison with the NTBC and, combined with the simplicity of the LTBC, ensures rapid and adequate calculations. According to the results, for the above-described TDP problem, it can be recommended to start the calculations with a moderate propagation step size D x and a transverse step D z in the range 0.4)0.7 m. With proper choice of the discretization step sizes, the LTBC may be useful in practical applications requiring real-time execu- tion and small computational resources. ABSTRACT: In this paper, we present a new topology for a tran- simpedance amplifier that allows postfabrication bandwidth adjustment by using a controloltage between the ground and the supply leel. Simulated results using HEMT and HBT technologies show a significant () bandwidth enhancement 25)45% with a negligible noise penalty. Q 2000 John Wiley & Sons, Inc. Microwave Opt Technol Lett 25: 47)51, 2000.