A novel met hod t o p artially compensate sigma2delta shap ed noise is p rop osed. By injecting t he comp en2 sation cur rent int o t he p assive loop f ilte r during t he delay time of t he p hase f requency detect or ( PFD) , a maximum reduction of t he p hase noise by about 16dB can be achieved. Comp a red t o ot he r compensation met hods , t he tech2 nique p rop osed he re is relatively simple and easy t o implement . Key building blocks f or realizing t he noise cancel2 lation , including t he delay va riable PFD and comp ensation cur rent source , a re sp ecially designed. Bot h t he behavior level and circuit level simulation results a re p resented.
