The Method for Improving the High-Speed of Classical and High-Temperature Operational Amplifiers with Current Negative Feedback

The paper considers a circuit technique to improve the high-speed of classical CBJT operational amplifiers (Op-Amps) with current negative feedback, the input stage of which is realized on the basis of the so-called “diamond” compound transistor and its modifications. It is shown that the reason for the relatively low values of the slew rate (SR) Op-Amps of this class, which are mass-produced by many microelectronic companies on micron technologies, is the presence of parasitic capacitances in the emitter circuits of the input transistors. To increase SR by 1-2 orders of magnitude (from 82 V/μs to 5000 V/μs) (when working of input transistors with emitter currents of the order of 100 μA), the introduction of a differentiating transients correction circuit into the classical Op-Amp circuit is recommended. This provides a significant improvement in SR without increasing the static current-consumption of the Op-Amp input stage. The results of computer simulating of CBJT Op-Amp in LTspice simulation software for micron process technology are presented. The considered circuitry is recommended for application in the structure of high-temperature analogue microcircuits based on wide-bandgap semiconductors (SiC, GaN, GaAs).