The Composite DDSA New Direct Digital Synthesizer Architecture

A new, low-power, high-speed, Direct Digital Synthesizer (DDS) arcbitecture is presented, called the Composite DDS (CDDS). A low-speed, high-resolution DDS is combinedwith high-speed, low-resolution phase accumulator and phase shifter via the serrodyne modulation technique. The low-speed circuitry provides the fine tuning while the high-speed circuitry provides come tuning. By minimizing the amount of circuitry required to clock at high-speed, dc power is conserved. The results from numeric simulations and a low-frequency proof-of-concept breadboard are presented. Progress on our 800 MHz CDDS development effort is described, followed by promise improved performance.