Gallium-Arsenide JFET Op-Amp with High Open-Loop Gain

The article presents studies of an operational amplifier (Op-Amp), which is based on gallium-arsenide field-effect transistors with a control p-n junction (GaAs JFet) and gallium-arsenide bipolar transistors (GaAs BJT). The peculiarity of the developed GaAs Op-Amp scheme is the use of a special active load in the input differential stage and the static current stabilization circuit of the differential stage's input transistors, which increases the Op-Amp gain. Comparisons of the proposed Op-Amp with Op-Amp with a classic input stage are given. The comparison proves that the proposed scheme design results in an increase in the open-loop GaAs Op-Amp's gain by 26 dB (up to 91 dB) and a decrease in the bias voltage systematic component from 3.48 mV to 1.4 μV. Two variants of Op-Amp buffer amplifiers are presented for their implementation on GaAs transistors. Computer simulation was carried out in the LTSpice XVII environment (USA) on GaAs transistors (JSC ''Minsk Research Institute of Radio Materials''). Developed circuitry applicable in modern interfaces sensors of physical quantities for use in a control device, instrumentation space, high-energy physics, and others.