Badania błędu współczynnika wzmocnienia wzmacniaczy z rezystancyjnym dynamicznym sprzężeniem zwrotnym

The analysis results of the amplification factor relative error of three kinds of amplifiers (non-inverting (Fig. 1,b), inverting (Fig. 2,a) and differential (Fig. 2,b)) based on resistors dynamic-feedback are presented in the paper. Such amplifiers are used for signal amplification in a wide dynamic range when, practically, the same value of the relative error of different amplification factors is required. It is shown that values of the mean and standard deviation of the mean amplification factor relative errors are proportional to the square of the resistance relative standard deviation: formulas (7), (8), (10). Moreover, it is shown that the mean error value do not practically depended on the number of used resistors. The error standard deviation decreases proportionally to the root square of the number of resistors. The characteristics of the amplification factor relative errors calculated by analytical formulas and by the Monte Carlo method for different number of feed-back resistors (from 2 to 100) are shown in Fig. 3. Based on the analysis of the influence of switch variation resistance on the amplification factor error, the condition (13) for correct choice of switches is obtained. It is shown that using resistors with the relative standard deviation of 0,1% and switches whose resistance deviation corresponds to the condition (13), it is possible to obtain the amplification factor accuracy of a few ppm.