СХЕМОТЕХНИЧЕСКИЕ МЕТОДЫ ПОВЫШЕНИЯ БЫСТРОДЕЙСТВИЯ ОПЕРАЦИОННЫХ УСИЛИТЕЛЕЙ НА ОСНОВЕ «ПЕРЕГНУТОГО» КАСКОДА

Abstract

Three circuit techniques are proposed that provide (with simultaneous use) an increase bymore than two orders of magnitude of the maximum output voltage slew rate (SR) of microelectronicoperational amplifiers (op-amps) based on bipolar transistors with a classical architecture,designed to operate in automatic control systems, radio engineering and communications, forexample, as drivers for ultra-high-speed analog-to-digital converters (EVIOAS150, EVIOAS350,AD9208, AD9691, 1273PV14, etc.). The considered op-amps contain a cascode input stage with anon-linear correction of the pass-through characteristic and a tracking circuit that increases theattenuation coefficient of the input common-mode signals and the noise suppression coefficient onthe power buses, as well as an intermediate stage based on a “folded” cascode. The use of a"folded" cascode makes it possible to increase the efficiency of using power supply voltages, aswell as to increase the unity gain frequency of the corrected op-amp. However, such an intermediatestage is an essential non-linear link that limits the maximum output currents that recharge theop-amp correction capacitor. The results of computer simulation of two modifications of theAmpSR1, AmpSR2 op amps, which differ from each other in the structure of a nonlinear parallelchannel, which eliminates the dynamic overload of a "folded" cascode, are presented. The relevanceof the research performed is related to the problems of import substitution in the class ofhigh-speed op-amps and the lack of new and promising ideas for increasing the SR of the op-ampbased on the simultaneous use of non-linear and differentiating transient correction circuits in thelarge signal mode among analog circuit designers. The considered circuit techniques are alsoeffective when using CMOS technological processes.