Marki Microwave offers surface mount broadband baluns for use with differential chips like ADCs, DACs, amplifiers, and many other applications involving A/D conversion and differential data transmission. Two different models are available with coverage over the 500 kHz to 6 GHz range. Both have a phase balance of +3 degrees, and a rise/fall time of 17 ps. See below for additional specifications and links to datasheets.