Статичні і динамічні характеристики високолінійних двотактних буферів напруги на біполярних транзисторах

Abstract

Push-pull voltage buffer devices (BD) are widely used in various measuring analog - digital systems, in which the electrical signal (voltage) sensor must be connected to the converter devices using circuits that have a high input impedance (at least tens and hundreds of mega), as well as low output impedance (no more than ~ 1.0 Ohm) to ensure a constant value of the transmission coefficient in the specified ranges of amplitudes and frequencies of the input signal. The article considered the proposed circuits of high-linear push-pull voltage buffers on bipolar transistors, including composite Shiklai transistors with a high slew rate of the output signal. An approach to the construction of a BD is proposed, based on the use of current reflectors, which operate in a push-pull balanced mode, which will provide high performance with a sudden change in the input voltage. We also investigated such small-signal static characteristics as the input and output resistance of the BD, the zero offset of the input current, as well as the linearity error in the range of input and output voltages. It is shown that in comparison with known devices, the proposed solutions have better performance. The dynamic characteristics of the proposed circuits, such as frequency response, nonlinear distortion coefficient in the frequency range of the output signal, as well as transient characteristics, are analyzed. It has been proved that the obtained indicators exceed those for circuits based on operational amplifiers. The quantitative values of the static and dynamic characteristics of the proposed BD are obtained, which can serve as recommendations for the selection of existing options depending on the parameters of the input signal sensors and the output load resistance.