Design of a GaAs operational amplifier using a self-backgating MESFET model including deep-level trap effects

A GaAs op amp has been designed using a self-backgating MESFET model which can simulate low-frequency anomalies and also has been fabricated by a 0.5-μm conventional MESFET technology. This model has been incorporated into PSPICE and includes an analytical DC and capacitance model with an RC network providing device symmetry. The op amp has three inverting stages, series-shunt feedback, and internal compensation with forward blocking to achieve unique stability. Measured data corresponds to simulations by the model. The authors have obtained a 35-dB open-loop gain in the high-frequency regime, 4-GHz gain-bandwidth product, an output voltage-swing range of -3.7 V to 3.4 V, and a total power dissipation of 0.46 W. The low-frequency anomalies of the GaAs amplifier are more accurately predicted using this model than with any other previous model