A Storage-Based Carry Randomization Technique for Spurs Reduction in Flying-Adder Frequency Synthesizer

Flying-adder architecture is an emerging on-chip frequency synthesis technology. Its theoretical foundation is the time-average-frequency concept introduced in 2008. During the past decade, the flying-adder technique has been successfully used in numerous commercial products. However, when fractional control word is used, its clock spectrum contains spurious tones due to the periodic carries generated from the fractional accumulation. In this brief, a storage-based technique is introduced to randomize the carries so that the discrete spurs can be converted into noise.