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Two Q-band monolithic low noise amplifiers have been designed and characterized. A study about depletion and enhancement mode HEMTs with the same technology has been performed in order to apply these results to the design of the low noise amplifiers. These circuits have been developed for being used in the Back End module of the radiometers in the European Scientific mission Planck, because there are not commercial circuits available in this frequency band. The main goals for these amplifiers are low noise with a small DC consumption. A minimum noise figure of 2.8 dB with an associated gain of 23.1 dB at 40.4 GHz has been measured for the E-HEMT MMIC LNA and its DC current consumption was 15.4 mA. The D-HEMT MMIC LNA has a minimum noise figure of 3 dB with an associated gain of 23.2 dB at 42 GHz and 30 mA of DC current consumption.

A novel combination of a packaged GaAs MMIC with a microstrip-coupled slot high performance 180° hybrid constitutes a downconverter, which provides the very low intermodulation level required by some TV applications. The packaged chip was mounted on a substrate together with a high performance and seldom-used MIC 180° hybrid. No adjustable filters are required due to the broadband behavior of the whole downconverter. This feature is required for cost reduction. A double-balanced mixer and the LO balun have been integrated in the same chip. A properly biased cold FET was used in the mixer to achieve low distortion frequency mixing. An active phase splitter was chosen as the LO balun in order to get small phase errors over a wide frequency band. The MIC 180° hybrid, which makes use of microstrip lines, slot lines and coupled-slot lines, was used as the RF balun. The topology used for this hybrid makes it very useful for balanced mixers, since there is no crossing of MIC transmission lines. On the other hand, there are no active elements, so no distortion is added to the downconverter. The hybrid was designed with an intensive use of a quasy-planar electromagnetic simulator. MMIC package modeling is also discussed in the paper. The MMIC was fabricated using the F20 process of the GEC Marconi foundry. Conversion losses of 8.5 dB can be obtained for the whole downconverter with a LO drive of 5.5 dBm. A 3rd order intercept point of 21 dBm of output power and a spectral purity in the complete RF frequency band of more than 70 dB were achieved.

This paper deals with FET's thermal static and dynamic properties for large signal operation. A very simple correction for traditional empirical equations for the Ids current source is proposed. The resulting mathematical approach takes into account the most important characteristics of these devices such as Power efficiency, Low frequency dispersion, Self heating and External temperature dependence. The experimental measurements and electrical modeling approaches has been done for three European foundries using very different topologies and technological process.

Several design procedures for oscillators are proposed and compared with commercial CAD tools and finally with measurements of fabricated voltage controlled MMIC prototypes. All of the proposed design techniques are easy to implement in any CAD package, or even to code in any Language. They provide, not only appropriate initial values for the components in more complete simulations, but also accurate final results. Measurements permit the validation of the whole design process, the models and the technology used. The Philips GaAs ER07AD process (Limeil, Paris) has been employed.

The two basic parts of a receiver operating in K band: a low noise amplifier and a mixer, have been designed and fabricated using Philips Microwave Limeil process D02AH. The circuits presented in this paper show very interesting results. For the low noise amplifier three stages were used obtaining good noise figures and gain results. The first two stages employ series feedback, and the last one uses parallel feedback. For the mixer, a recently proposed scheme, based on drain mixing was applied. On wafer measurements for both circuits are shown. The results show a reasonable performance and address weak points in modelling and technology for the design of enhanced prototypes.