Digitised spread spectrum clock generator using direct variable current modulation

A fully-integrated digitised spread spectrum clock generator (D-SSCG) using direct variable current modulation is presented. The proposed D-SSCG realises the spread spectrum function by only adding some micro-current source branches into a conventional clock generator. It has been fabricated in a 0.5 ??m BCD process and applied to a fly-back converter, among which the D-SSCG consumes 1.68 mW and occupies an area of 0.032 mm². Compared with other SSCGs, the proposed D-SSCG is simpler, and has advantages such as good robustness, small size, and low power consumption.