Noise and sensitivity optimization of a single-amplifier biquad

Many papers have dealt either with noise or sensitivity optimization of second-order active networks. In this article a joint optimization criteria is developed for a well-known single-amplifier biquad (SAB). The noise performance and the sensitivity properties of the SAB are described by two free network parameters, namely the resistor ratio
r^2
and the capacitor ratio
c^2
. A two-dimensional object function is left to minimize for either low-noise or low-sensitivity design. Curves which determine the best
r,c
values are given for both design objectives. A comparison indicates that only a slight sacrifice of the overall sensitivity properties is required by the optimum noise design, while a significant increase in output noise can result if the circuit is designed for minimum sensitivities.