Arsenide-Gallium Operational Amplifier with Increased Gain and Low Level of Systematic Component of Zero Offset Voltage

The circuitry of an arsenide-gallium operational amplifier (Op-Amp), which does not contain current mirrors that negatively affect its parameters, is considered. The essential feature of the proposed Op-Amp is the use of the so-called "folded" stage in the intermediate stage with a non-traditional circuit for establishing its static mode, which ensures minimization of the systematic component of the zero offset voltage (V <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">OS</inf> ). The low noise level of the proposed Op-Amp is provided by the realization of the input stage on nJFet transistors within the framework of combined technological processes allowing the use of nJFet field-effect and p-n-p bipolar transistors. The results of computer modeling of the amplitude-frequency response of GaAs Op-Amp are presented, which show that the voltage gain of the Op-Amp exceeds 90 dB, including at 5% variation of resistances of used resistors. The dependence of V <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">OS</inf> on 5% variation of resistors resistance of the Op-Amp circuit is investigated by Monte-Carlo method. The numerical values of V <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">OS</inf> are in the range from -21 μ V to -17.5 μ V.