M. L. de la Fuente

Resistive FET mixer conversion loss and IMD optimization by selective drain bias

This paper describes a dedicated nonlinear MESFET model extraction technique, which was used to accurately characterize the devices channel resistance nonlinearity. Plotting Ids(Vgs,Vds) Taylor series expansion coefficients across V/sub GS/ and V/sub DS/ revealed not only the presence of important minimum conversion loss bias, but also of in-band IMD sweet spots that were then used to optimize a FET resistive mixer performance.

Noise properties of the Planck-LFI receivers

The Planck Low Frequency Instrument (LFI) radiometers have been tested extensively during several dedicated campaigns. The present paper reports the principal noise properties of the LFI radiometers. A brief description of the LFI radiometers is given along with details of the test campaigns relevant to determination of noise properties. Current estimates of flight sensitivities, 1/f parameters, and noise effective bandwidths are presented. The LFI receivers exhibit exceptional 1/f noise, and their white noise performance is sufficient for the science goals of Planck.

LFI 30 and 44 GHz receivers Back-End Modules

The 30 and 44 GHz Back End Modules (BEM) for the Planck Low Frequency Instrument are broadband receivers (20% relative bandwidth) working at room temperature. The signals coming from the Front End Module are amplified, band pass filtered and finally converted to DC by a detector diode. Each receiver has two identical branches following the differential scheme of the Planck radiometers. The BEM design is based on MMIC Low Noise Amplifiers using GaAs P-HEMT devices, microstrip filters and Schottky diode detectors. Their manufacturing development has included elegant breadboard prototypes and finally qualification and flight model units. Electrical, mechanical and environmental tests were carried out for the characterization and verification of the manufactured BEMs. A description of the 30 and 44 GHz Back End Modules of Planck-LFI radiometers is given, with details of the tests done to determine their electrical and environmental performances. The electrical performances of the 30 and 44 GHz Back End Modules: frequency response, effective bandwidth, equivalent noise temperature, 1/f noise and linearity are presented.

Time-varying Volterra-series analysis of spectral regrowth and noise power ratio in FET mixers

This paper presents a direct and robust analysis technique for evaluating nonlinear distortion phenomena in FET mixers excited by multitone signals. Time-varying Volterra-series analysis has previously been proven to be appropriate for small-signal intermodulation-distortion calculations in mixers excited by simple RF signals. Spectral convolutions of the suitably mapped control voltages are introduced in this paper in order to solve the nonlinear current source calculations for narrow-band modulated or broad-band multicarrier RF signals. Simulations and measurements of a properly characterized resistive mixer validate the accuracy of this direct and noniterative analysis tool for spectral regrowth and noise-power-ratio prediction in such applications.

Simple nonlinearity evaluation and modeling of low-noise amplifiers with application to radio astronomy receivers

This paper describes a comparative nonlinear analysis of low-noise amplifiers (LNAs) under different stimuli for use in astronomical applications. Wide-band Gaussian-noise input signals, together with the high values of gain required, make that figures of merit, such as the 1 dB compression (1 dBc) point of amplifiers, become crucial in the design process of radiometric receivers in order to guarantee the linearity in their nominal operation. The typical method to obtain the 1 dBc point is by using single-tone excitation signals to get the nonlinear amplitude to amplitude (AM-AM) characteristic but, as will be shown in the paper, in radiometers, the nature of the wide-band Gaussian-noise excitation signals makes the amplifiers present higher nonlinearity than when using single tone excitation signals. Therefore, in order to analyze the suitability of the LNAs nominal operation, the 1 dBc point has to be obtained, but using realistic excitation signals. In this work, an analytical study of compression effects in amplifiers due to excitation signals composed of several tones is reported. Moreover, LNA nonlinear characteristics, as AM-AM, total distortion, and power to distortion ratio, have been obtained by simulation and measurement with wide-band Gaussian-noise excitation signals. This kind of signal can be considered as a limit case of a multitone signal, when the number of tones is very high. The work is illustrated by means of the extraction of realistic nonlinear characteristics, through simulation and measurement, of a 31 GHz back-end module LNA used in the radiometer of the QUIJOTE (Q U I JOint TEnerife) CMB experiment.

Low 1/f Noise 30 GHz Broadband Amplifiers for the Differential Radiometers of the Planck Surveyor Mission.

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 MMIC chips and filters assembly as well as experimental results are included.

Intermodulation Distortion Analysis of FET Mixers under Multitone Excitation

This paper presents an extension of the time-varying Volterra-series technique for evaluating intermodulation distortion (IMD) in FET mixers when excited by multitone signals. The mentioned nonlinear analysis tool is properly combined with an accurate device characterization in order to reproduce and control the FET distortion performance when it is employed for frequency conversion in small-signal regime. Good spectral regrowth and noise power ratio (NPR) predictions on a resistive mixer and on a class A amplifier confirm the validity of the proposed approach not only for time-varying but also for time-invariant applications.

Three Port Stability Analysis of Broadband Millimetre Wave MMIC Amplifier

The stability of microwave amplifiers is normally analysed as a two port network. An amplifier has at least a third port for biasing that might be considered for stability. Bias line impedances can lead to oscillations in amplifiers. Full stability analysis of a millimetre wave MMIC amplifier has been carried out using a three port scattering parameter test. Bias line impedance conditions to assure stable operation have been obtained

Effective Bandwidth Improvement Technique Based On Mismatch Analysis

The mismatch in cascaded two ports is a common cause of ripple increase and bandwidth reduction in broadband systems. A new mismatch factor, D, is defined to deal with the individual S21 and global S21 parameters in a cascaded network. The relationship between this D factor and the effective bandwidth is presented. This bandwidth can be improved inserting a matched attenuator. The method has been applied to a Q band broadband amplifier, based on two cascaded multistage MMIC amplifiers, used in a radiometer for a space application. Effective bandwidth has been improved inserting a series thin film resistor attenuator. The design expressions and criteria of such microstrip attenuators are described

Low noise high linearity ultra broadband monolithic amplifier using travelling-wave gain stages

A 2-20 GHz two-cascaded dual stage MMIC distributed amplifier (2-CDSDA) is presented in this paper. It consists of two cascaded dual-stage distributed amplifiers in order to achieve flat gain, good terminal match, low noise figure and high output power level. The topology of this amplifier joins the best features of the conventional distributed amplifiers and the cascaded distributed amplifiers. The measured small signal gain was 17 /spl plusmn/ 0.57 dB from 2 to 20 GHz. A minimum noise figure of 3 dB was achieved while a 14.9 dBm of output power was measured at the 1-dB compression point. The amplifier has been fabricated using the D01PH process provided by OMMIC. The chip size is 2 /spl times/ 1.5 mm/sup 2/.