有關hspice inverter chain design

ShengKuanLa@FB

不好意思，大學修積體電路導論，目前的作業出到inverter chain 但卡在這好久，麻煩前輩們解惑了!問題是4階inverter chain，條件給了minimum size還有基本的cl 1pf等等，我用了網路建議的f=3.8試看看，第一關跑圖就失敗了。。。tr0跑出來的圖形歪七扭八整片顏色。。。下面是我的gedit inv.sp


*****circuit****
, @5 p; n, z8 C3 S4 ~0 J7 ~+ k.subckt sub1 in out vdd vss
Mp1 out in vdd vdd P_18 w=3u l=0.18u m=1
# B3 I* O) W. b( `* K; BMn1 out in vss vss N_18 w=1u l=0.18u m=1
.ends sub1
# S5 l! @# c# t" n- t
.subckt sub2 in out vdd vss
2 _. Z7 P5 y8 H1 sMp2 out in vdd vdd P_18 w=11.4u l=0.18 m=2
Mn2 out in vss vss N_18 w=3.8u l=0.18u m=2
.ends sub2

.subckt sub3 in out vdd vss
, j2 v8 k  {$ V# V# dMp3 out in vdd vdd P_18 w=43.32u l=0.18u m=3
  ]5 a- s6 Z& L1 \Mn3 out in vss vss N_18 w=14.44u l=0.18u m=3
.ends sub3

3 Y- b* b' ^3 U% |6 a.subckt sub4 in out vdd vss
% \- E- a; v4 ^( Q, _8 @Mp4 out in vdd vdd P_18 w=164.6u l=0.18u m=4
8 a2 w0 f) N& `Mn4 out in vss vss N_18 w=54.87u l=0.18u m=4
.ends sub4

+ h- A* D2 o7 Q! z& G$ zxsub1 a b c 0 sub1
, q, R; V8 x  K' K: f7 u& ?xsub2 b d e 0 sub2
xsub3 d f g 0 sub3
' K* q1 q  H+ n* v- rxsub4 f h i 0 sub4
" s7 G. D2 x' s* gcl h 0 1pf


*****source******
vdd c 0 1.8
vdd e 0 1.8
vdd g 0 1.8
vdd i 0 1.8
3 j3 g) F0 H" G# U( fvgnd vss 0 0
vin a 0 pulse(0 1.8 1n 0.5n 0.5n 4.5n 10n)
. M; a. V4 F2 t*vin a 0 0.9
9 \! k# h: c; y" Q; ^
3 c: h5 z: {' R3 }3 a
3 e, @+ [$ L! O