In audio applications transformers are still employed due to several of their features. They are helpful at noise optimisation in circuits where two blocks are connected, having different output and input impedance. For example, when connecting a low-impedance microphone to an amplifier the input of which is of high impedance, not only the impedances are matched by the transformer, but the voltage gain obtained due to the high turns ratio lets the constructer decrease the gain of the amplifier stage as well, which contributes also to decreasing of the noise. Unfortunately, the design of such transformer is very complex, combining electrical, mechanical and geometrical issues. Therefore the authors of this paper decided to create an algorithm that helps the designer to design the transformer according to the requirements by means of Differential Evolution. The description of this method as well as its results is described in this paper
