Noise and Dynamic Range of Active Filters with Operational Amplifiers

Output noise spectral density and total rms output noise of filters with operational amplifiers can be determined by means of transformation of passive part of the filter under the condition that the noise model of the operational amplifier is known. This problem can be solved through sequential calculation of spot noise factors for cascaded passive and active parts of the transformed filter without feedback. In this paper, this approach is used for comparison and discussion of dynamic range of low-pass op-amp filters with positive and negative feedback.