Michel Pouysegur

X-band low phase distortion MMIC power limiter

Describes the design and performance of an 8-GHz MMIC (monolithic microwave integrated circuit) MESFET (metal-semiconductor FET) power limiter. This limiter incorporates a special gate biasing scheme and makes use of appropriate load conditions which reduce the unexpected phase variations experienced by the signal through the device. Measured performances (phase variations less than 8 over a 22-dB input power range) are found to be in agreement with the theoretical ones obtained from large signal simulations. >

A new concept to cancel insertion phase variation in MMIC amplitude controller

A concept which keeps a very low insertion phase variation in an analog monolithic microwave IC (MMIC) amplitude controller is presented. This new approach, applicable to dual-gate FET (DGFET) variable-gain amplifiers, is to connect an active variable load to the second gate of the DGFET. This load makes use of a cold FET (with Vds=0 V) whose impedance varies depending on the amplitude command of the circuit. Then, the cold FET compensates the insertion phase change introduced by the DGFET attenuation control over a wide dynamic range. Based on this principle, a C-band GaAs MMIC attenuator for active antenna application has been designed. The phase variation versus gain is always lower than +or-2 degrees over a 20-dB gain/attenuation range.<<ETX>>

Design of a low phase distortion GaAs FET power limiter

A simple design technique for a GaAs FET limiter exhibiting minimum phase distortion is presented. The key idea in removing phase distortion by selecting an appropriate device and designing a bias circuit is based on the observed properties of the gate barrier under large-signal conditions. Some illustrative examples and simulation results are presented. The proposed technique is suitable for monolithic microwave integrated circuit (MMIC) design. >

GaAs MMIC control functions for 3.7-4.2 GHz band active antenna

This paper describes the realization of gain and phase control function in GaAs microwave monolithic integrated circuit (mmic.). The measured performances are successfully compared with simulation results. The attenuator uses a dual-gatefet in order to adjust the level of the transmitted signal. The obtained dynamic range is 27 dB. The phase-shifter is made up of T and π networks connected in series and makes use of the capacitance variation of Schottky diodes to change the transmission phase. The phase shift reaches 115° at its maximum. Both circuits have been developed for a C-band beam forming network project for space communications.RésuméCet article décrit la réalisation de fonctions de contrôle de gain et de phase en technologie monolithique hyperfréquence GaAs. Les caractéristiques mesurées sont comparées aux résultats de simulation avec succès. L’atténuateur utilise untec double-grille afin d’ajuster le niveau du signal transmis. On obtient ainsi une dynamique de 27 dB. Le déphaseur est constitué par la mise en série de réseaux T et π et utilise la variation de capacité de diodes Schottky pour changer la phase du signal transmis. Le déphasage obtenu atteint 115° au maximum. Ces deux circuits ont été développés pour des réseaux de formation de faisceaux étroits dans la bande de 3,7 à 4,2 GHz pour télécommunications spatiales.

A Very Flat Variable Gain Amplifier MMIC for C-Band Satellite Receiver

This paper describes the design, the realization, and the performance of two versions of an analog C-band GaAs variable gain amplifier module suitable to application in C-band satellite receiver. This modules uses the ability of the Dual-Gate MESFET to provide variable gain. The highest obtained dynamic control range is 30 dB with very flat gain response within 3-5 GHz frequency range. Input and output return losses are always better than 15 dB and the phase variation versus gain lower than 10 degrees over a 20 dB gain/attenuation range. Two wafers of both versions were processed by THOMSON/DAG GaAs foundry using a 0.5 ¿m gate length technology. The overall manufacturing RF-yields are 45% and 60% for the two versions presented.

New generation of RF unit for radar altimeter

Alcatel developed a new generation of dual-frequency radar altimeter (POSEIDON 2) which works in C and Ku band. This article discusses about the radiofrequency unit (RFU) which plays a major role for the stringent performances of the altimeter. The compact RF unit has been designed with a modular concept. It uses the new advanced technologies: extensively use of MMIC, pHemt LNA and hybrid HFET power amplifiers. The transmitted peak power level is greater than 23W in C band and 7W in Ku band.

How MMIC Technology is Improving Satellite Transponders

Fiftecen years afier their fir-st deimonstitdion. MMICs are now rrapidis coniquerinig the world of space electronics, The driving force behlinid MMIC development have been miniaturization. cost reduction and higher reliability. MMICs have first been introduced into GEO Telecommunication satellites with a new generation of compact equipment. After these first convincing demonstrations. MMICs have now become an absolute necessity for turning into reality future satellites with active antennas. observation radars or future systems such as LEO constellations. The paper presents several major achievements for space programs and discusses about procedures to fly these advanced microclectronics.

Ku-Band MMIC's for Space-Borne Active Antenna

A full set of Ku-Band monolithic integrated circuits designed for a spatial telecommunication active antenna is presented. Low Noise Amplifier, Medium Level Amplifier, Mixer, Attenuator and Digital Phase-Shifter are detailed and the measured results are discussed. This is completed with the design and simulation of Digital and Analog Phase-Shifter whose processing is in progress.

A process-dependent worst-case analysis for MMIC design based on a handy MESFET simulator

The design of inexpensive MMIC modules implies a practical use of worst-case analysis. A reliable equivalent circuit model based on the unavoidable dispersion of uncorrelated technological parameters is proposed. The method relies on a convenient MESFET simulator which provides the DC, RF and noise parameters for any bias conditions. The input data are geometrical or electrical information readily available to the designer. The results of using the proposed model are compared with experimental data from several GaAs MMIC manufacturers. The model was also successfully applied to the design of a monolithic C-band amplifier. The forecasts of the worst-case analysis are compared with the experimental results for this amplifier. >