Automated synthesis of low noise amplifiers using s-parameter sets of passive elements

A modified technique for the automated design of microwave low noise amplifiers (LNAs) based on genetic algorithm (GA) is proposed. In contrast to previous GA-based approaches, it allows the synthesis of MMIC and PCB-based amplifier schematics with both lumped and distributed elements. During the synthesis, models of real passive elements in the form of measured S-parameter data sets can be used, this makes possible to directly account for element losses and parasitics. As an example, a double-stage 1-2 GHz LNA based on PCB and SMD components has been automatically synthesized, fabricated and measured. It is shown that the automated design can lead to practical circuits with performances close to commercial amplifiers.