High-speed digital-to-analog converter using Schottky diode samplers

A new digital-to-analog converter (DAC) structure employing Schottky diode samplers has been developed for very high-speed operation. Instead of switching used for conventional DACs, sampling of a digital bit stream is employed to retrieve the analog signals based on sampling theory. The sampled signals are added using an R-2R resistive ladder network. The samplers are designed to provide impedance matching for reflected signals. The DAC was fabricated as a hybrid circuit, and it achieved 1 Gs/s. Due to its transmission-line architecture, our design is scalable for use at much higher frequencies, as well as higher resolutions.