LTspice

LTspice introduction - 9 LPF的频域响应 

Version 4
SHEET 1 1672 680
WIRE 64 160 -16 160
WIRE 208 160 144 160
WIRE -16 192 -16 160
WIRE 208 192 208 160
WIRE -16 320 -16 272
WIRE 208 320 208 256
WIRE 208 320 -16 320
WIRE -16 336 -16 320
FLAG -16 336 0
SYMBOL cap 192 192 R0
SYMATTR InstName C1
SYMATTR Value 10nF
SYMBOL res 160 144 R90
WINDOW 0 0 56 VBottom 2
WINDOW 3 32 56 VTop 2
SYMATTR InstName R1
SYMATTR Value 10k
SYMBOL voltage -16 176 R0
WINDOW 123 24 124 Left 2
WINDOW 39 0 0 Left 2
SYMATTR InstName V1
SYMATTR Value ""
SYMATTR Value2 AC 1 0
TEXT 448 168 Left 2 ;keep the amp and phase not change, then check the freq response
TEXT -50 380 Left 2 !.ac dec 101 1 10k

将以上内容保存成1RC_lowpass_periodic_freq.asc文件，然后执行Run进行仿真，结果如下：