Physical Evaluation of Active inductances Controlled in GaAs MESFET Technology
Mohammed Salah Benbouza, Merabtine Nadjim · 2009
Two new structures of inductance which implement MESFET transistors are proposed in this article. The technological parameters of the components are those of 0.8µm MESFET technology. We will expose the advantages of these new structures such as the adjustable character of the value of the inductance like their limitation and we will compare them to those of the literature. The studies of RF inductances are justified by the keen demand of the applications in telecommunication such as filtering in continuous time, the controlled oscillators and decoupling. This basic element of analogical electronics is thus essential. Integrated passive inductances are limited by their low quality coefficient (1), the reproducibility of their values and the great silicon surface necessary to their synthesis for the RF applications whose frequency is a few gigahertz. It is moreover to note, that this problem of size involves an additional difficulty of characterization of the couplings existing between the various tracks which constitute the Some techniques were introduced to palliate or to lessen the impact of these defects (2, 3). These improvements are obtained with the detriment of the facility of design and require a high number of used metal layers, and also lead to the inductance modelling. The wire bonding was also explored in order to synthesize a passive inductance (4). However, this option does not present a strong integration and poses also the problem of the reproducibility of the inductance value. It thus remains held for certain applications. For a few years, another approach has known a renewal of attention on behalf of the analogicians originators: the active inductance. This revival is mainly due to better performances of the transistors which result from the technological improvements of the integrated circuits manufacturing processes. In addition to the adjustable aspect of the inductance, we can note the possibility of obtaining good quality factors (Q>5), a broader frequency range, as well as the independence between the inductance value and the circuit size. As we will point out, achievements were presented in GaAs technology for the high frequencies; others were presented in silicon bipolar technology for RF applications in the frequency band around the Giga-hertz. We will propose two new GaAs MESFET structures and will compare their characteristics to the other MESFET and bipolar structures of the literature.