gn7623233
Newbie level 6
Hi everyone~
I've designed a fully differential op amp
but my common-mode gain is large
how could I change the parameter to decrease my ACM to -20dB at DC
Thanks for the reply..
below is my hspice code
I've designed a fully differential op amp
but my common-mode gain is large
how could I change the parameter to decrease my ACM to -20dB at DC
Thanks for the reply..
below is my hspice code
Code:
.subckt op vdd vss vip vin vop von vcm clk
M1 3 vip 1 vss n_18 W=20u L=1.5u m=80
M2 4 vin 1 vss n_18 W=20u L=1.5u m=80
M11 1 vb0 vss vss n_18 W=10u L=1u m=10
M3 3 vb1 vdd vdd p_18 W=10u L=1u m=80
M4 4 vb1 vdd vdd p_18 W=10u L=1u m=80
M5 vop vb2 3 vdd p_18 W=20u L=1u m=30
M6 von vb2 4 vdd p_18 W=20u L=1u m=30
M7 vop vb3 5 vss n_18 W=5u L=1u m=20
M8 von vb3 6 vss n_18 W=5u L=1u m=20
M9 5 vb4 vss vss n_18 W=20u L=1u m=10
M10 6 vb4 vss vss n_18 W=20u L=1u m=10
***************************CMFB**********************************
Mcf1 d1 v+ d5 vss n_18 W=50u L=0.3u
Mcf2 vb0 vcm d5 vss n_18 W=50u L=0.3u
Mcf3 d1 d1 vdd vdd p_18 W=50u L=0.3u
Mcf4 vb0 d1 vdd vdd p_18 W=50u L=0.3u
Mcf5 d5 vb5 vss vss n_18 W=50u L=0.3u
R1 vop v+ 1x
R2 von v+ 1x
[ATTACH=CONFIG]135551._xfImport[/ATTACH]
Vb1 vb1 vss 1.1v
Vb2 vb2 vss 0.63v
Vb3 vb3 vss 1v
Vb4 vb4 vss 0.53v
Vb5 vb5 vss 0.6v
.ends
x1 vdd vss vip vin vop von vcm clk op
Vdd vdd gnd 1.8v
Vss vss gnd 0v
E+ vip vcm 7 vss 0.5
E- vin vcm 7 vss -0.5
VID 7 vss DC 0v ac 1
VIC vcm vss DC 0.9v
C1 vop gnd 4p
C2 von gnd 4p
*.tf v(vop) vid
.tf v(vop) vic
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