Version 4 SHEET 1 2040 1700 WIRE 176 320 576 320 WIRE 176 352 176 320 WIRE 176 432 176 464 WIRE 1056 288 1264 288 WIRE 1056 304 1056 288 WIRE 1056 384 1056 416 WIRE 1008 368 992 368 WIRE 992 368 992 416 WIRE 976 640 1040 640 WIRE 1120 640 1184 640 WIRE 1184 640 1184 688 WIRE 896 640 784 640 WIRE 576 320 720 320 WIRE 1184 752 1184 784 WIRE 1184 640 1264 640 WIRE 736 736 736 784 WIRE 784 752 784 784 WIRE 784 672 784 640 WIRE 832 112 832 144 WIRE 832 32 832 16 WIRE 832 16 1248 16 WIRE 832 1232 864 1232 WIRE 864 1232 864 1264 WIRE 944 1280 944 1232 WIRE 944 1232 864 1232 WIRE 992 1264 992 1232 WIRE 992 1232 1072 1232 WIRE 1152 1232 1184 1232 WIRE 1184 1232 1184 1264 WIRE 992 1344 992 1376 WIRE 992 1376 944 1376 WIRE 672 1376 672 1344 WIRE 672 1264 672 1232 WIRE 672 1232 752 1232 WIRE 864 1328 864 1376 WIRE 864 1376 672 1376 WIRE 992 1376 1184 1376 WIRE 1184 1376 1184 1328 WIRE 944 1328 944 1376 WIRE 944 1376 864 1376 WIRE 624 1280 576 1280 WIRE 624 1328 624 1456 WIRE 624 1456 1248 1456 WIRE 1248 1456 1248 1232 WIRE 1248 1232 1184 1232 WIRE 672 1392 672 1376 WIRE 1248 1232 1296 1232 WIRE 912 928 928 928 WIRE 1120 928 1184 928 WIRE 1184 928 1184 976 WIRE 832 928 576 928 WIRE 1184 1040 1184 1072 WIRE 1184 928 1264 928 WIRE 928 960 928 928 WIRE 928 928 1040 928 WIRE 928 1040 928 1072 WIRE 576 928 576 688 WIRE 736 688 576 688 WIRE 576 688 576 320 WIRE 720 320 1008 320 WIRE 576 928 576 1280 FLAG 176 464 GND FLAG 1264 288 A FLAG 1056 416 GND FLAG 992 416 GND FLAG 1184 784 0 FLAG 1264 640 B FLAG 736 784 0 FLAG 784 784 0 FLAG 1248 16 E FLAG 832 144 0 FLAG 720 320 in FLAG 1296 1232 D FLAG 672 1392 0 FLAG 1184 1072 0 FLAG 1264 928 C FLAG 928 1072 0 SYMBOL VOLTAGE 176 336 R0 SYMATTR InstName V1 SYMATTR Value PULSE(0 1 0 1n 1n 10 20) AC 1 SYMBOL E 1056 288 R0 WINDOW 123 24 132 Left 0 SYMATTR InstName E2 SYMATTR Value Laplace=1/(s**2+2*s+2) mtol=0.1 SYMBOL res 880 656 R270 WINDOW 0 32 56 VTop 0 WINDOW 3 0 56 VBottom 0 SYMATTR InstName R1 SYMATTR Value 1 SYMBOL ind 1024 656 R270 WINDOW 0 32 56 VTop 0 WINDOW 3 5 56 VBottom 0 SYMATTR InstName L1 SYMATTR Value 0.5 SYMBOL cap 1168 688 R0 SYMATTR InstName C1 SYMATTR Value 1 SYMBOL e 784 656 R0 SYMATTR InstName E1 SYMATTR Value 0.5 SYMBOL bv 832 16 R0 SYMATTR InstName B1 SYMATTR Value V=0.5+0.5*exp(-time)*(-sin(time)-cos(time)) SYMBOL e 672 1248 R0 SYMATTR InstName E3 SYMATTR Value 1 SYMBOL e 992 1248 R0 SYMATTR InstName E4 SYMATTR Value 1 SYMBOL cap 848 1264 R0 SYMATTR InstName C2 SYMATTR Value 1 SYMBOL cap 1168 1264 R0 SYMATTR InstName C3 SYMATTR Value 1 SYMBOL res 736 1248 R270 WINDOW 0 32 56 VTop 0 WINDOW 3 0 56 VBottom 0 SYMATTR InstName R2 SYMATTR Value 1 SYMBOL res 1056 1248 R270 WINDOW 0 32 56 VTop 0 WINDOW 3 0 56 VBottom 0 SYMATTR InstName R3 SYMATTR Value 1 SYMBOL res 816 944 R270 WINDOW 0 32 56 VTop 0 WINDOW 3 0 56 VBottom 0 SYMATTR InstName R4 SYMATTR Value 2 SYMBOL ind 1024 944 R270 WINDOW 0 32 56 VTop 0 WINDOW 3 5 56 VBottom 0 SYMATTR InstName L2 SYMATTR Value 0.5 SYMBOL cap 1168 976 R0 SYMATTR InstName C4 SYMATTR Value 1 SYMBOL res 912 944 R0 SYMATTR InstName R5 SYMATTR Value 2 TEXT 104 32 Left 0 !;ac oct 10 .001 1MEG TEXT 104 0 Left 0 !.tran 0 5 0 1m TEXT 104 80 Left 0 ;Any experiment with window and nfft doesn't reduce the error.\nLaplace=1/(...) window=10 nfft=1024\n \nMike's suggestion helped: \n----------------------------------------\nLaplace=1/(s**2+2*s+2) mtol=0.1\nand \n.OPTIONS reltol=0.0001 TEXT 808 504 Left 0 ;The realization with E,R,L,C\n1/()1+jwRC+(jw)^2*LC) = 0.5/(1+s+0.5*s^2))\nRC=1 LC=0.5 TEXT 792 -40 Left 0 ;The precise solution for the step response TEXT 664 1144 Left 0 ;Y(s)=G(s)/(1+G(s)) G(s) = 1/(1+s)^2 = 1/(1+jwRC)^2\nY(s) = 1/(1+s)^2 / (1 + 1/ (1+s)^2) TEXT 488 -32 Left 0 ;H(s)=1/(s**2+2*s+2) TEXT 768 256 Left 0 !.options reltol=.0001 ; <-- reltol is tightened! TEXT 824 808 Left 0 ;The realization with R,L,C\n1/()1+jwRC+(jw)^2*LC) = 0.5/(1+s+0.5*s^2))\nRC=1 LC=0.5