Experimental Study of AM and PM Noise in Cascaded Amplifiers

An experimental study of amplitude modulation (AM) and phase modulation (PM) noise spectra in cascaded amplifiers was carried out as a function of the number of amplification stages and the input power. Flicker and white noise contributions were determined, as well as effective noise figure (NF) from AM and PM noise spectra from small-signal to large-signal regimes. Simultaneous measurements of AM and PM noise were performed, and associated correlation was measured as a function of the offset frequency from the carrier. Measurements exhibited, in general, quite low AM–PM correlation levels both in the flicker and white noise parts of the spectrum. In some particular amplifier configurations, however, measurements showed some peaks in the correlation at some specific input power levels in the transition zone, from a quasi-linear to strong compression. The results show that the effective noise figure decreases with the number of stages for a given carrier output power level.This research was partly funded by Basque Country Government (GIUIT1104-16)

Estudio del efecto de las impedancias fuera de banda sobre la intermodulación en un amplificador a FET utilizando un modelo gran señal

GaAs Field Effect Transistors are widely used for medium- and high-power amplifiers. This kind of amplifiers have great influence in the performance of a communication system, as far as cost, power consumption, and signal degradation of the transmitter are concerned. Thus, accurate nonlinear models of the transistors are needed in order to predict their behaviour. In this paper, a large-signal continuous model is extracted from measurements of a transistor. Then, a simple amplifier based on the device has been designed, and simulations are carried out in order to predict the performance of a power amplifier built with this type of transistor. Finally, effects arising from baseband and 2nd-harmonic load impedances are analysed by a load-pull method, and their influence on the IMD behaviour is discussed

Control óptico de un oscilador MMIC en banda Ku

This paper shows the latest results research on the optical control of a GaAs chip monolithic Voltage Controlled Oscillator, and is an extension of previous work realized by our group in the field of opticalmicrowave interaction. The oscillator was originally designed for the transmitter stage of a VSAT communications front-end system in the 14.5 GHz band. The possibilities of optical control of the VCO by illumination of the PHEMT transistor are demonstrated through measurements of the oscillation output power and frequency. An optical control range of 8dB of oscillation output power and up to 400MHz of oscillation frequency has been obtained

Control óptico de un amplificador MMIC de AsGa en banda S

This paper shows the results of research on the optical control of a GaAs chip monolithic amplifier, and is an extension of previous work by our group in the field of optical-microwave interaction . The amplifier was originally for the transmitter stage of an indoor mobile communications system in the 2.4 GHz band. The possibilities of optical control of this amplifier are evidenced as follows: if the amplifier operates with the same biasing, the gain can be optically controlled from a condition of almost isolation, (gain less than - 5 dB), up to an active condition, (gain greater than 10 dB), which gives a range of optical control of about 15 dB. At the same time, the optical control provides an improvement of the input and output matching in a range of 12dB and 6dB, respectively. This optical control promises an interesting control of gain and matching for other microwave FET based active devices

Modelado, simulación y medida de la compresión en LNAs para aplicaciones de astronomía

In this work, system level modelling and realistic simulation and measurement results of a 31 GHz Back-End Module (BEM) Low-Noise Amplifier (LNA), designed for the QUIJOTE CMB (Q U I JOint TEnerife CMB) experiment radiometer, are reported. The signals received by radiometers can be identified as continuous spectre gaussian white noise signals. This makes necessary time-domain simulation techniques and appropriate models for the realistic analysis of radiometers behaviour. The measured-based modelling of one BEM´s LNA, its simulation in nominal conditions and the measurement of the nonlinear characteristic by using filtered white noise excitation signals, will be shown. Typically, in the LNAs design process the linearity is not taken into account but, as we will see, in the radiometers case, the nature of gaussian noise excitation signals makes amplifiers to present higher nonlinearity in their characteristics than when using single tone excitation signals. Therefore, in order to analyze the suitability of the LNAs nominal operation, linearity figures of merit have to be obtained, but using realistic excitation signals. In this paper, the LNAs nonlinear characteristics with gaussian noise excitation signals have been obtained by simulation and measurement

Caracterización de la compresión en LNAs para aplicaciones de astronomía

In this work, system level modelling and realistic simulation and measurement results of a 31 GHz Back-End Module (BEM) Low-Noise Amplifier (LNA), designed for the QUIJOTE CMB (Q U I JOint TEnerife CMB) experiment radiometer, are reported. The signals received by radiometers can be identified as continuous spectre gaussian white noise signals. This makes necessary time-domain simulation techniques and appropriate models for the realistic analysis of radiometers behaviour. The measured-based modelling of one BEM´s LNA, its simulation in nominal conditions and the measurement of the nonlinear characteristic by using filtered white noise excitation signals, will be shown. Typically, in the LNAs design process the linearity is not taken into account but, as we will see, in the radiometers case, the nature of Gaussian noise excitation signals makes amplifiers to present higher nonlinearity in their characteristics than when using single tone excitation signals. Therefore, in order to analyze the suitability of the LNAs nominal operation, linearity figures of merit have to be obtained, but using realistic excitation signals. In this paper, the LNAs nonlinear characteristics with gaussian noise excitation signals have been obtained

Modelado y simulación realista del módulo posterior de un radiómetro: aplicación al instrumento a 31 GHz del experimento QUIJOTE

In the reported work, an efficient modelling method is applied to the circuits of the 30 GHz Back End Module of the QUIJOTE experiment radiometer. In particular, efficient models of two LNAs, a band pass filter and a detector has been obtained. These models allow realistic time-domain BEM simulation by using Gaussian noise excitation signals. Simulation results have been reported, showing good agreement with the BEM expected operation. On the other hand, time-domain realistic simulations will provide valuable information about BEM behaviour previously to the receiver definitive implementation

Demostrador del módulo posterior del radiómetro de 30 GHZ de Planck

A radiometer back end module based on broadband low noise amplifiers and band pass filters is presented. Low noise amplifiers are multistage HEMT MMIC chips. A 20% of bandwidth at 30 GHz have been achieved. The passband is fixed by coupled lines microstrip filters. A complete module containing two identical branches of amplification and filtering stages with a gain greater than 30 dB has been developed. The low 1/f noise behavior of gain fluctuations allows the module to be used as the back end module for the differential radiometers in the european scientific mission Planck. Details of the MMICs chips and filters assembly as well as experimental results are included

New Generation Compact Linear Accelerator for Low-Current, Low-Energy Multiple Applications

A new compact linear proton accelerator project (named LINAC 7) for multiple low-current applications, designed and built in-house at the Beam Laboratory of the University of the Basque Country (UPV/EHU) is described. The project combines the University, a research technology center and a private company with the aim of designing and building a compact, low-current proton accelerator capable of accelerating particles up to 7 MeV. In this paper, we present an overview of the accelerator design, summarize the progress and testing of the components that have been built, and describe the components that are being designed that will allow us to achieve the final desired energy of 7 MeV.This research was funded by the Basque Government, Department of Economic Development, Sustainability and Environment under codes Elkartek KK-2020/00003 and KK-2021/00029, and by the University of the Basque Country UPV/EHU Research Group ref. GIU18/196

A Novel Micro- and Nano-Scale Positioning Sensor Based on Radio Frequency Resonant Cavities

In many micro- and nano-scale technological applications high sensitivity displacement sensors are needed, especially in ultraprecision metrology and manufacturing. In this work a new way of sensing displacement based on radio frequency resonant cavities is presented and experimentally demonstrated using a first laboratory prototype. The principle of operation of the new transducer is summarized and tested. Furthermore, an electronic interface that can be used together with the displacement transducer is designed and proved. It has been experimentally demonstrated that very high and linear sensitivity characteristic curves, in the range of some kHz/nm; are easily obtainable using this kind of transducer when it is combined with a laboratory network analyzer. In order to replace a network analyzer and provide a more affordable, self-contained, compact solution, an electronic interface has been designed, preserving as much as possible the excellent performance of the transducer, and turning it into a true standalone positioning sensor. The results obtained using the transducer together with a first prototype of the electronic interface built with cheap discrete elements show that positioning accuracies in the micrometer range are obtainable using this cost-effective solution. Better accuracies would also be attainable but using more involved and costly electronics interfaces.The authors are grateful to CICYT and to the Basque Government for partial support of this work though projects DPI2011-24821 and IT-381-10, respectively