[正在讨论]求助，用ADS设计一个CASCODE 放大器，工作在1.5GHz

这个是小弟的本科毕业设计，刚刚接触哦ADS. Sh$U-ch@  
附件里是我的原理图，用的是TSMC 0.18um d$Em\*C  
B(Y.`L? %E  
我就是不懂为什么S参数仿真，S21，总是0， h#O"Q+J9n  
几个管子也工作正常，有高手能 .. QK7e|M  
\_>?V5(  

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MOSFET          M2 %B0w~[!4}  
~R'BU=!;F  
Id               0.00681703 [~!.a\[RW  
Ig               0 X;(oz]tr$  
Is              -0.00681703 K:uQ#W.&  
Ib              -2.90831e-010 L2<+#O#  
Power            0.00585403 / Z1Wy-Z  
Gm               0.0649125 =#
b4c>  
Gmb              0.0190901 XnPJC'  
Gds              0.00172897 e"lD`*U8R  
Vth              0.515084 ~ t"n%SgY  
Vdsat            0.129541 8V,"Id][  
Capbd            1.41607e-013 @|E;}:?u  
Capbs            0 cB_pyX9Z  
CgdM             0 T^d#hl.U  
CgbM             0 m'3OGvd  
CgsM             0 {[my"n2  
DqgDvgb          3.38433e-013 ,cPkx~w0  
DqgDvdb         -7.29362e-014 87+.pM|t%  
DqgDvsb         -2.31091e-013 wG;}TxrLS  
DqbDvgb         -3.56057e-014 /G{&[X<4U  
DqbDvdb          9.14332e-017 :&qC<UD  
DqbDvsb         -4.37657e-014 tI"wVr  
DqdDvgb         -7.34416e-014 HE@-uh  
DqdDvdb          7.33247e-014 ~37R0`C  
DqdDvsb          1.61682e-016 sC!1B6:  
Vgs              0.63502 `!<x"xKu  
Vds              0.858735 3_C98ClE  
Vbs              0 O(WEgz  
--------------------------------- f_~}X#._  
MOSFET          M3 Ko4)0&  
Tm%WWbc  
Id               0.00681703 ?ISI[hoc  
Ig               0 ?U}sQ;c$  
Is              -0.00681703 U 7EHBW  
Ib              -1.51348e-012 @>+^W&  
Power            0.00437153 %N7gT*B:  
Gm               0.0639939 1bT'u5&  
Gmb              0.0189861 =jsx(3V  
Gds              0.00201249 SgyqmYTvZw  
Vth              0.515736 r^fxyN2V  
Vdsat            0.132356 ;tXB46  
Capbd            1.49251e-013 l&\tf`~  
Capbs            0 yB 1I53E  
CgdM             0 0BT;"B1  
CgbM             0 $xLEA\s  
CgsM             0 ful]OLV+  
DqgDvgb          3.394e-013 BN_!Y)Fl  
DqgDvdb         -7.29588e-014 =_K%$y*  
DqgDvsb         -2.32616e-013 ?OdV1xB  
DqbDvgb         -3.5463e-014 9qnuR'BDu  
DqbDvdb          7.38502e-017 ~K4k'   
DqbDvsb         -4.39711e-014 ^6ExW>K  
DqdDvgb         -7.35916e-014 ,:c:6Y^  
DqdDvdb          7.33893e-014 K3a>^g  
DqdDvsb          2.90752e-016 dko[  
Vgs              0.641265 #8S [z5 `  
Vds              0.641265 Z`^ K%P=  
Vbs              0 ^xzE^"G6  
--------------------------------- ( P  
MOSFET          M1 jM6uT'Io  
0@o;|N"i  
Id               0.00029577 _e;N'DZ  
Ig               0 k,a,h^{}j  
Is              -0.00029577 jQY>9+t  
Ib              -6.5309e-013 JqL<$mSep  
Power            0.00018782 x&QNP  
Gm               0.00289473
"ugX /r$_  
Gmb              0.000820531 (qNco8QKu3  
Gds              8.78399e-005 }P05eI  
Vth              0.514934 A"Tc^Ij  
Vdsat            0.112369 }*xC:A%aS  
Capbd            7.60237e-015 7^n,Tig  
Capbs            0 58M'r{8_  
CgdM             0 j7QBU  
CgbM             0 5Xp$yX =  
CgsM             0 (K^YD K  
DqgDvgb          1.73162e-014 Ti0 (VdY  
DqgDvdb         -3.63987e-015 cZPbD;e:  
DqgDvsb         -1.20679e-014 c ,Qw;  
DqbDvgb         -2.19273e-015 '~ j
y  
DqbDvdb          2.30314e-018 7~nIaT  
DqbDvsb         -1.67041e-015 -OHvK
0~  
DqdDvgb         -3.672e-015 pI'8>_o  
DqdDvdb          3.66248e-015 %{N>c:2I$  
DqdDvsb          1.36212e-017 plzE  
Vgs              0.63502 516VQ<?B  
Vds              0.63502 -fb1cv~N  
Vbs              0

  ++

从图上看感觉L2,C1的一端好像没有和管子M2/M3的G/D连在一起, 节点的颜色是红的. 好好检查一下.