What is the difference between a transformer and a balun?
The basic difference between a transformer and a wire-wound balun is the way the coils of each are wound and the way they are used. A transformer has primary and secondary windings that are isolated from each other. The secondary can be D.C biased differently than the primary, usually through a secondary center tap. The secondary winding may also have taps for providing different voltages to different parts or a circuit, or completely isolated secondaries to drive different parts of the circuit. The transmission line balun has a D.C connection between the primary and one secondary port and does not not, typically, provide multiple secondary ports or signal taps. The balun is capable of very broad band performance, compared with the ordinary transformer, with very little signal loss. Transformers are specified with, among other things, a given turns or voltage ratio, where baluns are specified in terms of impedance ratios. A balun with a 1:2 impedance ratio will have an impedance on its
