A Phase Interpolation Direct Digital Synthesizer With A Digitally Controlled Delay Generator

We have developed a new type of phase interpolation direct digital synthesizer (DDS) with a digitally controlled delay generator. The new DDS is similar to a sine output DDS in that it produces low spurious signals (spurs), but it does not require a sine look-up table. Periodic jitter in the most significant bit (MSB) of the DDS accumulator is reduced with the digitally controlled delay generator. Experimental results confirm successful frequency synthesizer operation in which the spurious signal level is successfully reduced to less than that the MSB of the accumulator.