Electronic – Impedance matching using transformer vs other circuits, what is the difference


We can use transformers to carry out impedance matching. However, using various configurations of BJT circuit can achieve the same effect. Here I am talking about common collector, common base and common emmiter configurations. In different configurations we get different input output impedances that can be controlled to much extent.

When do we use a transformer to match impedances and when do we use other circuitry. I understand that if we have very high power applications than transofmer can provide isolation, but what about other not so high voltage applications?

Best Answer

I'd use a transformer when I want to isolate one signal from another. The transformer provides galvanic separation between two circuits and this is needed in several applications. One that springs to mind is a data coupler between a rotating machine and a static data receiver - you can't use wires but, you can use a rotating transformer to couple the data.

I've used near-field data transfer of modulated data as well and, in effect, antennas have become a transformer.

You can find RS485 chips that now embody isolation transformers and, ADI have a series of data coupling chips that incorporate tiny transformers to provide galvanic isolation.