High-Order Low-Noise Microwave Active Recursive Filters

In this article, we present a three-pole lownoise microwave active recursive filter obtained by a cascade association of three first-order recursive cells. To minimize the noise factor of the filter we study two topologies of first-order recursive filter. For each topology we determine the values of the optimal couplings and gain needed to obtain the minimum noise factor. We validate our study with simulated and measured results.