A multi-band high gain mixer and quadrature signal generator allows a receiver system to receive signals at multiple frequency bands without requiring significant hardware duplication. A single mixer directly receives any of three communication frequency bands such as Universal Mobile Telecommunication System (UMTS), Personal Communication Services (PCS), Digital Communication System (DCS), and Japan and US W-CDMA 800 bands without amplification. A Serial-Parallel Interface selectably forwards RF signals within the receiver's frequency channels to the mixer for demodulation into in-phase (I) and quadrature (Q) signals at a common IF output from the multi-mode receiver. Significant power and cost advantages are attained by elimination of duplicate mixers and amplifier stages.