An analytic model for estimating the length of the velocitysaturated region in GaAs MESFETs

An analytical model is presented for estimating the length of the portion of an FET channel with velocity saturated carriers. The model is based on previous work proposed by Pucel et al. [1974, 1975], and has been adapted to remove discontinuities between extreme bias conditions. The need for complicated numerical solutions has also been removed making the model suitable for use with circuit simulators. Results obtained from the model agree well with previously proposed models over a wide range of bias conditions where velocity saturation can be either dominant or negligible, depending on the overall channel length and bias conditions     

Monolithic tunable active inductor with independent Q control

A 1.1-GHz fully integrated GaAs MESFET active inductor is presented in this paper. Both the inductance and loss resistance are tunable with the inductance independent of series loss tuning. The measured loss resistance is tunable over a -10- to +15-Ω range with a corresponding change in inductance of less than 10% at 100 MHz and less than 4% for frequencies above 500 MHz. The inductance is tunable from 65 to 90 nH. Considerably larger bandwidths can be achieved depending on the fabrication technology employed and the intended application of the circuit     

A monolithic 6 GHz quadrature frequency doubler with adjustable phase offset

A 6 GHz frequency doubler with quadrature outputs generated from a differential single phase input is presented. The phase offset between the in-phase and quadrature outputs can be digitally controlled in linear steps for use in an automated calibration algorithm. The design nominally achieves standard deviations in quadrature phase error and amplitude balance of 0.4/spl deg/ and 0.1dB, respectively. This is demonstrated with a single sideband (SSB) mixer that realizes an average uncalibrated sideband rejection of 48.2 dB which improves to 55.8 dB post-calibration under nominal conditions.