Polyphase clock generator

Abstract

A polyphase clock generator for use in clock data recovery (CDR) includes a phase selector and a four-to-eight phase converter further including a plurality of delay paths, switches, and phase interpolators. The switches switch over the delay paths so as to select a group of delay paths suited to a clock frequency which is determined in advance. A plurality of reference clock signals with a predetermined phase difference (e.g. 90°) therebetween is selectively delayed while passing through the selected group of delay paths. The phase interpolators interpolate the delayed reference clock signals, passing through the selected group of delay paths, into the reference clock signals, thus generating a plurality of clock signals. The phase selector selectively combines the clock signals with a mixing ratio according to clock data recovery, thus generating a plurality of recovery clock signals with a precise phase difference (e.g.) 45°) therebetween.

Dependencies are inferred from the claim text.