Balun circuit with a cancellation element in each coupled line

摘要

A Marchand balun cirucit having a pair of coupled lines of quarter wavelength for dividing and/or combining signals with the same amplitude and opposite phase with each other is improved by inserting a cancellation element between said pair of coupled lines. Said cancellation element may be a transmission line, a capacitor, or an inductor which improves amplitude difference error and phase difference error of a pair of outputs by controlling phase velocity for an even mode so that phase velocity for an even mode becomes equal to that for an odd mode. Thus, a balun circuit with wide operation band, and less error of amplitude difference and phase difference is obtained.