Digital signal processing algorithms for adaptive loop gain and frequency detection in Bang-Bang CDR

Abstract

As the operating speed of the CDR gradually increases, digital CDRs with high operation reliability are increasingly preferred. The complex signal processing capabilities of digital circuits can provide a variety of functions that conventional analog CDRs could not. This dissertation presents a digital signal processing method that extracts optimal loop gain of CDR and frequency of input data from BBPD output. We describe the concept and operation of a smart CDR that incorporates these algorithms and a loop filter. The proposed algorithms were measured with ICs fabricated at 40nm and 65nm, respectively.