EFFECT OF COMPONENT TOLERANCES IN LOW FREQUENCY SELECTIVE AMPLIFIERS- AN ANALYSIS.

Abstract

Two types of resistance-capacitance networks, namely the Wien  bridge and the twin-T, used in low frequency selective amplifiers are  analyzed in respect of the effect of the error in each component value  on the null of the network and consequently on the selectivity of the  amplifier. It is shown that when networks are designed for obtaining maximum selectivity with a given amplifier, the Q-factor of the amplifier is relatively sensitive to small errors in the network components. This  sensitivity can be reduced by suitably choosing the ratios of the components of the network, though, as a consequence, a higher amplifier gain  would be necessary for obtaining the same selectivity. Quantitative relations are developed between the rate of variation of Q with the component error factor and the relevant component ratios of the networks.