四位超前进位加法器原理,四位超前进位加法器原理图

('超前进位加法器原理74283为4位超前进位加法器，不同于普通串行进位加法器由低到高逐级进位，超前进位加法器所有位数的进位大多数情况下同时产生，运算速度快，电路结构复杂。其管脚如图1所示：图174283管脚图其真值表如下所示：表14位超前进位加法器真值表由全加器的真值表可得Si和Ci的逻辑表达式：1定义两个中间变量Gi和Pi：当Ai＝Bi＝1时，Gi＝1，由Ci的表达式可得Ci＝1，即产生进位，所以Gi称为产生量变。若Pi＝1，则Ai·Bi＝0，Ci＝Ci-1，即Pi＝1时，低位的进位能传送到高位的进位输出端，故Pi称为传输变量，这两个变量都与进位信号无关。将Gi和Pi代入Si和Ci得：进而可得各位进位信号的逻辑表达如下：根据逻辑表达式做出电路图如下：2逻辑功能图中有2输入异或门，2输入与门，3输入与门，4输入与门，2输入或门，3输入或门，4输入或门，其转化成CMOS晶体管图如下：34电路网表如下：xor2.subcktxor2abcdfmxorpa1avddvddpmosl=2w=8mxorpbfd1vddpmosl=2w=8mxorpc2bvddvddpmosl=2w=8mxorpdfc2vddpmosl=2w=8mxornafa30nmosl=2w=4mxornb3b00nmosl=2w=4mxorncfc40nmosl=2w=4mxornd4d00nmosl=2w=4.endsxor2and2.subcktand2abfmandpafavddvddpmosl=2w=4mandpbfbvddvddpmosl=2w=4mandnafa10nmosl=2w=4mandnb1b00nmosl=2w=4.endsand2and3.subcktand3abcfmandpafavddvddpmosl=2w=4mandpbfbvddvddpmosl=2w=4mandpcfcvddvddpmosl=2w=4mandnafa10nmosl=2w=6mandnb1b20nmosl=2w=6mandnc2c00nmosl=2w=6.endsand3and4.subcktand4abcdfmandpafavddvddpmosl=2w=4mandpbfbvddvddpmosl=2w=4mandpcfcvddvddpmosl=2w=4mandpdfdvddvddpmosl=2w=4mandnafa10nmosl=2w=8mandnb1b20nmosl=2w=8mandnc2c30nmosl=2w=8mandnd3d00nmosl=2w=8.endsand45or2.subcktor2abfmorpa1avddvddpmosl=2w=8morpbfb1vddpmosl=2w=8mnafa00nmosl=2w=4mnbfb00nmosl=2w=4.endsor2or3.subcktor3abcfmorpa1avddvddpmosl=2w=12morpb2b1vddpmosl=2w=12morpcfc2vddpmosl=2w=12mnafa00nmosl=2w=4mnbfb00nmosl=2w=4mncfc00nmosl=2w=4.endsor3or4.subcktor4abcdfmorpa1avddvddpmosl=2w=16morpb2b1vddpmosl=2w=16morpc3c2vddpmosl=2w=16morpdfd3vddpmosl=2w=16mnafa00nmosl=2w=4mnbfb00nmosl=2w=4mncfc00nmosl=2w=4mndfd00nmosl=2w=4.endsor4not.subcktnotafmnotpafavddvddpmosl=2w=4mnotnafa00nmosl=2w=2.endsnot反相器or21.subcktor21abfxor2ab1or2xnot1fnot.endsor212输入或门or31.subcktor31abcf6xor3abc1or3xnot1fnot.endsor313输入或门or41.subcktor41abcdfxor4abcd1or4xnot1fnot.endsor414输入或门xor21.subcktxor21abfxmaA5notxnbB5notxxorabA5B5fxor2.endsxor212输入异或门and21.subcktand21abfxand2ab1and2xnot1fnot.endsand212输入与门and31.subcktand31abcfxand3abc1and3xnot1fnot.endsand313输入与门and41.subcktand41abcdfxand4abcd1and4xnot1fnot.endsand414输入与门xxor211a1b1p1xor21xxor212a2b2p2xor21xxor213a3b3p3xor21xxor214a4b4p4xor21xand211a1b1g1and21xand212a2b2g2and21xand213a3b3g3and21xand214p1c0m0and217xor211m0g1c1or21进位C1xand311p2p1c0m1and31xand215p2g1m2and21xor312g2m1m2c2or31进位C2xand411p3p2p1c0m3and41xand313p3p2g1m4and31xand216p3g2m5and21xor412m3m4m5g3c3or41进位C3xxor215p1c0s1xor21输出s1xxor216p2c1s2xor21输出s2xxor217p3c2s3xor21输出s3xxor218p4c3s4xor21输出s4.include"c:\\lib\\130nm_bulk.l"tt.optscale=0.05u.globalvddgndvddvdd01.2va1a10pulse1.21.220n1f1f30n100nva2a20pulse0020n1f1f30n100nva3a30pulse0020n1f1f30n100nva4a40pulse0020n1f1f30n100nvb1b10pulse1.21.220n1f1f30n100nvb2b20pulse1.21.2201f1f30n100nvb3b30pulse0020n1f1f30n100nvb4b40pulse1.21.220n1f1f30n100nvc0c00pulse004n1f1f0n100n.tran1n100n.plottranv(s1).plottranv(s2).plottranv(s3).plottranv(s4).end8',)