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A simple-but-efficient calibration-spur reduction technique is introduced that utilises the digital-and-analogue hybrid return-to-zero (HRZ) method in a current-steering DAC employing a round-robin-fashioned background current-source calibration scheme. A simulation with a 12 b 500 MS/s current-steering DAC showed 9.9 and 7.8 dB improvements in the spur-free dynamic range and signal-to-noise + distortion ratio, respectively, owing to the reduced calibration spur by the proposed HRZ technique.

It is reported that the spur-free dynamic range (SFDR) of an optically homodyned serrodyne signal depends on the relative phase difference between the beating optical waves. By optimising this parameter, a 1 MHz tone with 63 dB SFDR has been synthesised, which is the highest serrodyne SFDR ever reported

A modified dynamic element matching algorithm, based on splitting the unit element set into subsets, is proposed. Simulations show that it can improve the spur-free dynamic range of data-weighted averaging significantly, without degrading its signal-to-noise ratio.

Injection locking is demonstrated to improve the analogue performance of long wavelength VCSELs. The third-harmonic spur-free dynamic range was improved by 9 dB/Hz/sup 2/3/ to be 93 dB/Hz/sup 2/3/, and the modulation bandwidth was increased twofold.

Methods to simplify digital frequency synthesizers based on the co-ordinate rotation digital computer (CORDIC) algorithm are presented. Application of these methods leads to performance enhancement, compared with the topologies previously proposed in the literature. For a given output precision, hardware resources are reduced and spur-free dynamic range is increased.