The LT5557 active mixer is optimized for high linearity, wide dynamic range downconverter applications. The IC includes a high speed differential LO buffer amplifier driving a double-balanced mixer. Broadband, integrated transformers on the RF and LO inputs provide singleended 50 interfaces. The differential IF output allows convenient interfacing to differential IF filters and amplifiers, or is easily matched to drive a single-ended 50 load, with or without an external transformer.