The image reject signal chain consists of two mixers, with their RF input ports driven from a splitter. Half of the source power will be delivered to each mixer RF input port (1 and 2). The LO ports are fed by a quadrature LO source. The in phase LO source drives the in phase mixer, sometimes called the I mixer. The quadrature (Q) mixer LO source is shifted 90 degrees from the I mixer LO source. The IF ports of both mixers (3 and 4) drive a 90 degree hybrid, which phase-shifts the Q IF signal and then combines the I and Q signals at the IF output (5).