Telescopic op amp simulation problem

m1 1 2 3 4 nmos l=2u w=2u

Good day everybody,

I'm using National Instrument's Multisim 10 to design and simulate a fully differntial telescopic op amp. The design picture, design details and simulation files are associated.
The problem is that I can't get the NMOS telesdcopic transistors to work in saturation, the entire biasing voltage is distributed on the PMOS transistors.

Plz help if anybody knows where's the problem.








Currents in P,NMOS current mirrors are 0.17 mA both. Currents in each differential branch are 1.5 mA both.


Mb2: (PMOS current mirror – 2N6804)
L=1u W=118.5u
* RS=0 RD=0 LD=0 CBD=0 CBS=0 CGBO=0
.MODEL MM PMOS LEVEL=1 IS=1e-32
+VTO=-0.7 LAMBDA=0.1KP=3.555m
+CGSO=3.44747e-06 CGDO=1e-11
.

M5-7 (PMOS telescopic – 2N6804)
M1 9 7 8 8 MM L=1u W=1111u
* RS=0 RD=0 LD=0 CBD=0 CBS=0 CGBO=0
.MODEL MM PMOS LEVEL=1 IS=1e-32
+VTO=-0.7 LAMBDA=0.1KP=33.33m
+CGSO=3.44747e-06 CGDO=1e-11

M1-4: (NMOS telescopic – 2N7000)
Cgs 2 3 12.3E-12
Cgd1 2 4 27.4E-12
Cgd2 1 4 6E-12
M1 1 2 3 3 MOST1 W=2.5m L=2u
M2 4 2 1 3 MOST2 W=2.5m L=2u
D1 3 1 Dbody
.MODEL MOST1 NMOS(Level=3 Kp=75m W=2.5m L=2u Rs=20m Vto=0.7 Rd=1.186)
.MODEL MOST2 NMOS(VTO=-0.7 Kp=75m W=2.5m L=2u Rs=20m)
.MODEL Dbody D(Is=125f N=1.023 Rs=1.281 Ikf=18.01 Cjo=46.3p M=.3423
+ Vj=.4519 Bv=60 Ibv=10u Tt=161.6n)


M9: (Iss NMOS – 2N7000)
Cgs 2 3 12.3E-12
Cgd1 2 4 27.4E-12
Cgd2 1 4 6E-12
M1 1 2 3 3 MOST1 W=0.8m L=2u
M2 4 2 1 3 MOST2 W=0.8m L=2u
D1 3 1 Dbody
.MODEL MOST1 NMOS(Level=3 Kp=24m W=0.8m L=2u Rs=20m Vto=0.7 Rd=1.186)
.MODEL MOST2 NMOS(VTO=-0.7 Kp=24m W=0.8m L=2u Rs=20m)
.MODEL Dbody D(Is=125f N=1.023 Rs=1.281 Ikf=18.01 Cjo=46.3p M=.3423
+ Vj=.4519 Bv=60 Ibv=10u Tt=161.6n)



Mb1: (NMOS current mirror – 2N7000)
Cgs 2 3 12.3E-12
Cgd1 2 4 27.4E-12
Cgd2 1 4 6E-12
M1 1 2 3 3 MOST1 W=45.33u L=2u
M2 4 2 1 3 MOST2 W=45.33u L=2u
D1 3 1 Dbody
.MODEL MOST1 NMOS(Level=3 Kp=1.36m W=45.33u L=2u Rs=20m Vto=0.7 Rd=1.186)
.MODEL MOST2 NMOS(VTO=-0.7 Kp=1.36m W=45.33u L=2u Rs=20m)
.MODEL Dbody D(Is=125f N=1.023 Rs=1.281 Ikf=18.01 Cjo=46.3p M=.3423
+ Vj=.4519 Bv=60 Ibv=10u Tt=161.6n)
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telescopic op amp simulation setting

you have to use CMFB, without CMFB your circuit doesn't work.