understanding building and using baluns and ununs download

The outputs of the balun may or may not be the same impedance as the input.The two outputs are not necessarily matched.Unlike an isolator or circulator, a balun is a reciprocal device that can be used bidirectionally.The unbalanced input is matched to the input transmission line impedance (usually 50 Ω).In time domain this means the voltage of one balanced output is the negative of the other balanced output.In frequency domain this means the outputs have a 180° phase shift.The two outputs will be equal and opposite.

A balun is a three port power splitter, similar to a Wilkinson or resistive power divider.It is most succinctly described by the required (ideal) S-parameters: Finally we will discuss the applications of baluns and how to determine what kind of balun is required for a several different purposes.Ī balun is any three port device with a matched input and differential outputs. Next we will define generic balun specs, which we then use to discuss the different types of baluns and their properties. First we will define what a balun is, what it does, and how it is different from other components. The need for high speed, low noise data transfer has driven the advancement of the balun to higher frequencies and superior performance.ĭespite these advancements, information about baluns remains scattered and confusing this application note seeks to resolve this problem by clarifying the basic characteristics of baluns. Baluns have long been ubiquitous in low frequency audio, video, and antenna driving applications.

Since then designs have evolved dramatically, and applications have evolved beyond driving differential antennas to include balanced mixers, amplifiers, and signaling lines of all types. The balun has a long and illustrious history, first documented in the literature as a device to feed the television transmitting antenna for the Empire State Building1 in 1939.

Understanding building and using baluns and ununs download