Circuitry Features of the Gallium Arsenide Operational Amplifier and its Basic Functional Units

The article discusses the features of the construction of gallium arsenide (GaAs) operational amplifiers (OpAmps), as well as their input, intermediate and output stages. OpAmp circuit solutions have been developed that provide low values of the zero offset voltage systematic component (lower than 1 μV) and an increased open-loop voltage gain (155 dB). Mathematical analysis of the main parameters of OpAmp is performed. The results of computer modelling of an OpAmp based on combined GaAs manufacturing process by the OJSC “Minsk Research Institute of Radio Materials”, which implement n-channel FET and p-n-p bipolar transistors, are presented. The GaAs OpAmps considered in the article can be used in various analogue transducer and ADCs (signal transducers, active filters, active front end etc.), including their implementation for the microwave ranges.