Conventional AFC ● Frequency comparison by counter 0 Selected fyco is closest to N*fref,not(N+.F)*frer >Residual fractional error.F*frer is generated fref Counter Shift VCO band Comparator 千d Counter N+.F Divider fvco Multiband VCO DSM 2009 IEEE International Solid-State Circuits Conference 2009 IEEE 9© 2009 IEEE International Solid-State Circuits Conference © 2009 IEEE 9 Conventional AFC • Frequency comparison by counter • Selected fvco is closest to N* fref, not ( N+. F)* fref ¾ Residual fractional error . F* fref is generated ref div ref vco