Noise Considerations in Cascaded Single-Stage Distributed Amplifiers

Exact formulas for the noise parameters of a cascaded single-stage distributed amplifier (CSSDA) utilizing GaAs MESFETs as active devise have been developed. The method is rigorous in the sense that it takes into account the contribution of all the noise sources of the amplifier as a two port network. The analysis is worked out by using chain or ABCD matrices of the transistors and interstage networks. Finally, after the dependence of the noise characteristics on the circuit parameters is discussed, the noise figure of a DC-25 GHz three stage module is computed and compared with simulation results using the full nonunilateral model of the transistor. The result of the simulation for the completed amplifier is in good agreement with the calculated noise parameters by our method