第8期 He Jie et al.A CMOS Fully Integrated Frequency Synthesizer with Stability Compensation 1529 cell could be implemented with the true-single- Table 1 Design parameters summary phase-clock(TSPC)logic. Kvco 20-40MHz/V N 4000-4200 Icp 20A fe 10kHz b 10 R 460kn PM3 C1 112pF Cz 11.2pF fre 250kHz So 1 PM PM2 (mx 1.68 Cuin 0.63 00000 Damping factor variation is simulated with the technology variations.In typical CMOS technolo- gy,suppose△R/R≈0.2and△C/C≈0.1 at the worst corner.Current can always be trimmed ex- NM NM2 ternally and of variation limited in 10%.Due to the nonlinearity of the VCO tuning curve,Kvco varies more widely than other parameters.From LC-VCO analysis,variation of Kvco is within 50%by careful Fig.5 Differential complementary cross-coupled-bega- design[.In this example,the design value is set at tive-G-VCO with cross-switched varactor 30MHz/V after simulation.The division ratio N will also contribute to the variation factor.In this 4 Simulation and verification verification,the division ratio contributes little to variation factor because of its relative small The fully integrated frequency synthesizer is change.Then,the worst negative variation factor is implemented in 0.25um CMOS RF technology.Mi- 0.26 and the worst positive variation factor is 2.6. crographic is shown in Fig.6.The synthesized fre- The simulated step responses are shown in Fig.7, quency ranges from 1 to 1.05GHz with resolution including curves with no variation,worst negative 250kHz.This results in a large frequency-dividing variation,and worst positive variation.Negative ratio of about 4000.The parameters are summa- variation tends to make the loop under-damping rized in Table 1. more obviously than positive variation.The reason is that the dominant pole @ps in positive variation is 1.4 a-0.26 1.2 a=2.6 1.04 1.02 a=2.6 0.25 0.6 1.00 0.98 a=1 0.4 0.96 0.94 0.2 0.92 1.52.02.53.03.5 00 051052025303540 t/10s Fig.6 Micrographic of frequency synthesizer Fig.7 Step responses for technology variations第&期 I=.8=9=+>S( *)AW,UN99L(?F=JD7F=RUD=^N=?:L,L?FG=<8]=D@8FG,F7K898FL)E6M=?<7F8E? :=99:EN9R K=86M9=6=?F=R @8FGFG=FDN=0<8?J9=0 MG7<=0:9E:a%/,-)&9EJ8:> U8J>5 18HH=D=?F879:E6M9=6=?F7DL:DE<<0:ENM9=R0K=J70 F8X=0?6 V)W@8FG:DE<<0<@8F:G=RX7D7:FED U 2JR<:C?J9GCGLX@AJMJNC?J9G /G=HN99L8?F=JD7F=RHD=^N=?:L<L?FG=<8]=D8< 86M9=6=?F=R8?"‘!5$6)AW,ZUF=:G?E9EJL>A80 :DEJD7MG8:8<<GE@?8?U8J>#>/G=<L?FG=<8]=RHD=0 ^N=?:LD7?J=<HDE6$FE$‘"5CI]@8FGD=<E9NF8E? !5"aI]>/G8<D=<N9F<8?797DJ=HD=^N=?:L0R8X8R8?J D7F8EEH7KENF2""">/G=M7D76=F=D<7D=<N6670 D8]=R8?/7K9=$> U8J># A8:DEJD7MG8:EHHD=^N=?:L<L?FG=<8]=D /7K9=$ 1=<8J?M7D76=F=D<<N667DL NV)W !"#2"AI])V G 2"""#2!"" T)- !"$* E: $"aI] H $" B 2#"a’ A$ $$!MU A! $$‘!MU ED=H !5"aI] +" $ )67\ $‘#& )68? "‘#4 176M8?JH7:FEDX7D87F8E?8<<86N97F=R@8FGFG= F=:G?E9EJLX7D87F8E?<>(?FLM8:79)AW,F=:G?E9E0 JL$<NMME<=,B)B("‘!7?R ,A)A("‘$7FFG= @ED<F:ED?=D>)NDD=?F:7?79@7L<K=FD866=R=\0 F=D?799L7?REHX7D87F8E?9868F=R8?$"h>1N=FEFG= ?E?98?=7D8FLEHFG=V)WFN?8?J:NDX=$NV)W X7D8=< 6ED=@8R=9LFG7?EFG=DM7D76=F=D<>UDE6P)0V)W 7?79L<8<$X7D87F8E?EHNV)W8<@8FG8?5"h KL:7D=HN9 R=<8J?-$4. >(?FG8<=\76M9=$FG=R=<8J?X79N=8<<=F7F 4"AI])V7HF=D<86N97F8E?>/G=R8X8<8E?D7F8E G @89979<E:E?FD8KNF=FEFG=X7D87F8E?H7:FED>(?FG8< X=D8H8:7F8E?$FG=R8X8<8E?D7F8E:E?FD8KNF=<98FF9=FE X7D87F8E? H7:FED K=:7N<= EH 8F< D=97F8X= <6799 :G7?J=>/G=?$FG=@ED<F?=J7F8X=X7D87F8E?H7:FED8< "‘!#7?RFG=@ED<FME<8F8X=X7D87F8E?H7:FED8<!‘#> /G=<86N97F=R<F=MD=<ME?<=<7D=<GE@?8?U8J>3$ 8?:9NR8?J:NDX=<@8FG?EX7D87F8E?$@ED<F?=J7F8X= X7D87F8E?$7?R @ED<F ME<8F8X= X7D87F8E?>+=J7F8X= X7D87F8E?F=?R<FE 67a=FG=9EEM N?R=D0R76M8?J 6ED=EKX8EN<9LFG7?ME<8F8X=X7D87F8E?>/G=D=7<E? 8<FG7FFG=RE68?7?FME9=*M48?ME<8F8X=X7D87F8E?8< U8J>3 ,F=MD=<ME?<=<HEDF=:G?E9EJLX7D87F8E?< $5!%