Motivation Dual-conversion DVB-T architecture needs a 1.175-to-2GHz frequency synthesizer Loop bandwidth changes due to VCO tuning gain (Kvco)and division ratio Variation of loop bandwidth may result in loop instability and phase noise deterioration To ensure loop bandwidth constant,some techniques are explored... RFIC-Atlanta June 15-17,2008RFIC – Atlanta June 15-17, 2008 3 Motivation • Dual-conversion DVB-T architecture needs a 1.175-to-2GHz frequency synthesizer • Loop bandwidth changes due to VCO tuning gain (KVCO) and division ratio • Variation of loop bandwidth may result in loop instability and phase noise deterioration • To ensure loop bandwidth constant, some techniques are explored