这么难的问题, 俺一般是让电脑来计算。
Version 4 SHEET 1 1216 680 WIRE 112 96 0 96 WIRE 256 96 192 96 WIRE 0 128 0 96 WIRE 256 128 256 96 WIRE 0 272 0 208 WIRE 256 272 256 208 WIRE 256 272 0 272 WIRE 256 304 256 272 FLAG 256 304 0 FLAG 0 96 tp01 FLAG 256 96 tp02 SYMBOL ind 240 112 R0 SYMATTR InstName L1 SYMATTR Value 1e-6 SYMBOL res 96 112 R270 WINDOW 0 32 56 VTop 2 WINDOW 3 0 56 VBottom 2 SYMATTR InstName R1 SYMATTR Value 1 SYMBOL voltage 0 112 R0 WINDOW 3 -124 -96 Left 2 WINDOW 123 -75 106 Left 2 WINDOW 39 0 0 Left 2 SYMATTR InstName V1 SYMATTR Value PWL repeat forever 0 0.6 157229e-9 0.6 157230e-9 -0.6 314449e-9 -0.6 314459e-9 0.6 endrepeat SYMATTR Value2 AC 1 TEXT -130 328 Left 2 !.tran 0 1e-3 0 1e-9