“…The mixer's gain mismatch can be minimized by using a proper architecture like passive mixer and good layout techniques, but the LO phase imbalance is usually over 1 degree even with sophisticated calibration, which implies that no more than 40 dB image rejection can be achieved. Therefore, to achieve over 60 dB image rejection ratio, double-quadrature architecture, which can relax the matching requirement of the LO, is preferred [6,7]. As shown in Figure 2(b), the double-quadrature architecture handles the down-conversion with complex LO and complex RF signals.…”