Noise analysis of second-order analogue active filters

The output noise of continuous-time active filters is analysed in general terms by directly inserting device noise sources in an equivalent block diagram. This removes some of the restrictions imposed by previous methods of noise-source referral and permits more meaningful analytical optimisation. Design recommendations for minimising noise in a wide range of realisations then emerge. This allows performance comparisons of active-RC, active-R and OTA-C circuits