Division-Ratio-Based AFC Π E=Ncntr-Ndec Counter VCO Clock Comparison fvco Ndec=p*(N.Fdec) 口门 Decoded by Band shift VCO Ref.Clock ÷p division ratio AFC: Iref 一一一 27 ●●●20 2122232425●●●224 Division RatioX XXXXXXX.XXX XX●●。X N.F Integer modulus Fractional modulus Decoding modulus(N.Fdec) Fractional error Decoding→Ndec Ndec is decoded from the division ratio N.Fdec, >Residual fractional error is reduced to 24*fer 2009 IEEE International Solid-State Circuits Conference 2009 IEEE 10© 2009 IEEE International Solid-State Circuits Conference © 2009 IEEE 10 Division-Ratio-Based AFC • Ndec is decoded from the division ratio N.Fdec, ¾ Residual fractional error is reduced to 2-4 * fref