A quadrature or 90˚ hybrid is a special type of power splitter that creates a 90˚ (π/2 radians) phase shift between the two outputs. This phase shift is both broadband (unlike a delay line) and relative (between the outputs). Marki quadrature hybrids are created by building a backwards wave coupler (similar to our stripline directional couplers) with a 3 dB coupling value and creating equal power outputs (for other methods and their merits or demerits, see this tech note). Important figures of merit include amplitude balance, phase balance, and isolation between output ports. Among the many applications of quadrature hybrids are balanced amplifiers and the quadrature signal generation necessary for IQ and image reject mixers.