[SOLVED] SRAM butterfly curve

warlocklw said:

Greetings. I wish to ask for method to create butterfly curve. It's V(q) vs V(qb). When I use DC analysis, I can sweep voltage q and observe voltage at qb, but the voltage q will be a linear increase straight line. If I were to observe the transition of q and qb, i will have to use transient analysis. How do I create a v(q) vs v(qb) butterfly curve? Thanks in advanced.
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SRAM4
.option abstol=1e-6 reltol=1e-6 post ingold

.hdl "bsimcmg.va"
.include "modelcard.nmos"
.include "modelcard.pmos"

.global vdd!
.param vdd=1
Vvdd! vdd! gnd dc=vdd

* --- Source ---
VWL vWL gnd dc=0
Vqq q gnd

* --- Inverter Subcircuit ---
.subckt inverter vin vout vddi vss
Xp1 vout vin vddi vddi pmos1 TFIN=15n L=30n NFIN=10
Xn1 vout vin vss vss nmos1 TFIN=40n L=30n NFIN=10
.ends

* --- 1 unit SRAM ---
Xinv_top qb q vdd! 0 inverter
Xinv_bot q qb vdd! 0 inverter

* --- Access Transistor ---
Xn5 qb vWL BLB gnd nmos1 TFIN=20n L=30n NFIN=10
Xn6 q vWL BL gnd nmos1 TFIN=20n L=30n NFIN=10

* --- Analysis ---
.dc Vqq 0 1 0.01
.print dc v(q) v(qb)
.end

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