Noise design of active feedback resonator BEF

It is shown that, in a filter design system which introduces noise temperature into the active feedback resonator (AFR), the AFR band elimination filter (BEF) can be designed using techniques for the conventional passive BEF. In this system, the passive BEF circuit used for electrical design is also useful for the noise analysis of the AFR BEF. This analysis reveals that the noise figure (NF) value of the AFR BEF can be calculated from the noise temperatures of AFRs. The optimum NF value is obtained by minimizing these noise temperatures. The noise design of a three-pole AFR BEF is discussed. It is found that the observed NF of the three-pole AFR BEF agrees well with the theoretical values deduced from the designed S-parameters and the observed noise temperatures of the AFRs