1,721,059 research outputs found
S-band digital downconverter for radar applications based on a GaAs MMIC fast sample-and-hold
No full textA digital coherent-downconverter
configuration is described whose operation
principle is based on the theory of subharmonic
sampling for narrowband waveforms. This
configuration uses a fast sampler, operating at
microwave frequencies, for directly demodulating
the in-phase and quadrature components of a
complex input waveform, yielding a sampled
sequence in a suitable format for subsequent
analogue-to-digital conversion. Unlike the
conventional double-conversion coherentsuperheterodine
architecture, the proposed
configuration offers attractive features in terms of
cost and complexity and appears particularly
suitable for the implementation of the front-end
unit in a coherent receiver. An experimental
prototype, based on a very fast GaAs MMIC
sample-and-hold (SH) circuit, has been
implemented for validating the operation
principle. Complex demodulation of a 1 GHz
input waveform is demonstrated, with 6-bit
equivalent accuracy
Equivalent circuit model of GaAs MMIC‐coupled planar spiral inductors
No full textThe article describes a lumped component model which accounts for coupling between inductors in GaAs MMIC design. The model was developed using a full-wave approach. The validity of the proposed circuit has been successfully tested. Experimental results are reported to validate the model
Small-signal distributed FET model consistent with device scaling
No full textA distributed modelling approach for micro- and millimetre-wave FETs is presented. Model identification is directly carried out on the bases of S-parameter measurements and electromagnetic analysis of the device layout, without requiring cumbersome optimisation techniques. Experimental results confirm that the model is consistent with device scaling
Small-signal distributed FET modeling through electromagnetic analysis of the extrinsic structure
No full textThe paper presents a new approach to the distributed modeling of high frequency transistors suitable for CAD applications. In particular, electromagnetic simulation is adopted to characterize the extrinsic part of the electron device in terms of a multi-port scattering matrix without introducing approximations based on lumped components. Experimental and simulation results for 0.5 μm GaAs MESFETs with different gate widths preliminary confirm the consistency of the proposed approach
Anew approach to FET model scaling and MMIC design based on electromagnetic analysis
No full textA new approach, using electromagnetic analysis, is proposed for field-effect transistor model scaling and monolithicmicrowave integrated-circuit (MMIC) design. It is based on an empirical distributed modeling technique where the active device is described in terms of an external passive structure connected to a suitable number of internal active sections. On this basis, an equivalent admittance matrix per gate unit width is obtained which, as confirmed by experimental results provided in this paper, is consistent with simple scaling rules. The same technique can also be adopted for a "global approach" to MMIC design where complex electromagnetic phenomena are also taken into account. An example of application concerning this aspect is presented. © 1999 IEEE
Integrated active transponder for ISM-band applications
No full textThe paper describes a multifunction GaAs MMIC dedicated to ISM-band short range microwave link application. The chip was designed to satisfy the typical transponder system specifications and to be easily adaptable to different transponder architectures. Experimental results are reported and discussed
A new approach to FET model scaling and MMIC design based on electromagnetic analysis
No full textA new approach, using electromagnetic analysis, is proposed for field-effect transistor model scaling and monolithic-microwave integrated-circuit (MMIC) design. It is based on an empirical distributed modeling technique where the active device is described in terms of an external passive structure connected to a suitable number of internal active sections. On this basis, an equivalent admittance matrix per gate unit width is obtained which, as confirmed by experimental results provided in this paper, is consistent with simple scaling rules. The same technique can also be adopted for a “global approach” to MMIC design where complex electromagnetic phenomena are also taken into account. An example of application concerning this aspect is presente
Millimeter-wave FET modeling using on-wafer measurements and EM simulation
No full textElectron device modeling is a challenging task at millimeter-wave frequencies. In particular, conventional approaches based on lumped equivalent circuits become inappropriate to describe complex distributed and coupling effects, which may strongly affect the transistor performance. In this paper, an empirical distributed FET model is adopted that can be identified on the basis of conventional S-parameter measurements and electromagnetic simulations of the device layout. The consistency of the proposed approach is confirmed by robust scaling properties, which enable millimeter-wave small-signal S-parameters to be predicted as a function of the device periphery and number of gate fingers. Moreover, it is shown how the model identified on the basis of standard S-parameter measurements up to 50 GHz can be efficiently exploited in order to obtain reasonably accurate small-signal prediction up to 110 GHz. Extensive experimental validation is presented for 0.2-μm pseudomorphic high electron-mobility transistors device
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