.lib "../sky130_fd_pr/models/sky130.lib.spice" tt

**.subckt 4bitdac_tb
x1 x1_inp1 x1_inp2 x1_vdd 0 x1_d0 x1_d3 x1_d1 x1_out_v x1_d2 4bitdac
V1 x1_vdd 0 dc 3.3
V2 x1_d0 0 PULSE 0 1.8 0ns 1p 1p 5u 10u
V3 x1_d1 0 PULSE 0 1.8 0ns 1p 1p 10u 20u
V4 x1_inp2 0 dc 0
V5 x1_inp1 0 dc 3.3V
V6 x1_d2 0 PULSE 0 1.8 0ns 1p 1p 20u 40u
V7 x1_d3 0 PULSE 0 1.8 0ns 1p 1p 40u 80u

**.ends

* expanding   symbol:  /home/harshitha/Desktop/xschem/xschem_library/4bitdac.sym # of pins=9


.subckt 4bitdac inp1 inp2 vdd gnda d0 d3 d1 out_v d2
*.ipin inp1
*.ipin inp2
*.iopin vdd
*.iopin gnda
*.ipin d0
*.ipin d3
*.ipin d1
*.opin out_v
*.ipin d2
R1 x1_vref5 x2_vref1 250
x3 x1_out_v vdd out_v d3 gnda x2_out_v TG2
x1 inp1 x1_vref5 vdd gnda d0 d2 d1 x1_out_v 3bitdac
x2 x2_vref1 inp2 vdd  gnda d0 d2 d1 x2_out_v 3bitdac
.ends

* expanding   symbol:  /home/harshitha/Desktop/xschem/xschem_library/3bitdac.sym # of pins=8


.subckt 3bitdac inp1 inp2 vdd gnda d0 d2 d1 out_v
*.ipin inp1
*.ipin inp2
*.iopin vdd
*.iopin gnda
*.ipin d0
*.ipin d2
*.ipin d1
*.opin out_v
R1 x1_vref5 x2_vref1 250 
x1 vdd inp1 gnda x1_out_v d1 d0 x1_vref5 2bitdac
x2 vdd x2_vref1 gnda x2_out_v d1 d0 inp2 2bitdac
x3 x1_out_v vdd out_v d2 gnda x2_out_v TG2
.ends

* expanding   symbol:  /home/harshitha/Desktop/xschem/xschem_library/2bitdac.sym # of pins=7

.subckt 2bitdac  vdd vref1 gnda out_v d1 d0 vref5
*.ipin vref1
*.ipin vref5
*.ipin d0
*.ipin d1
*.iopin vdd
*.iopin gnda
*.opin out_v
x1 x1_inp1 vdd x1_vout d0 gnda x1_inp2 TG2
x2 x2_inp1 vdd x2_vout d0 gnda vref5 TG2
x3 x1_vout vdd out_v d1 gnda x2_vout TG2
R1 x1_inp1 vref1 500
R2 x1_inp2 x1_inp1 500
R3 x2_inp1 x1_inp2 500
R4 vref5 x2_inp1 250
.ends


* expanding   symbol:  /home/harshitha/Desktop/xschem/xschem_library/TG2.sym # of pins=6

.subckt TG2  inp1 vdd vout din 0 inp2
*.ipin inp1
*.ipin inp2
*.opin vout
*.ipin din
*.iopin vdd
*.iopin gnda

XM1 dinb din 0 0 sky130_fd_pr__nfet_01v8 L=0.15 W=0.6 
XM2 dinb din vdd vdd sky130_fd_pr__pfet_01v8 L=0.15 W=1.2

XM7 dd dinb 0 0 sky130_fd_pr__nfet_01v8 L=0.15 W=0.6
XM8 dd dinb vdd vdd sky130_fd_pr__pfet_01v8 L=0.15 W=1.2

XM3 vout dinb inp2 inp2 sky130_fd_pr__nfet_01v8 L=0.15 W=0.6
XM4 inp1 dd vout vout sky130_fd_pr__nfet_01v8 L=0.15 W=0.6

XM5 vout dinb inp1 inp1 sky130_fd_pr__pfet_01v8 L=0.15 W=1.2
XM6 inp2 dd vout vout sky130_fd_pr__pfet_01v8 L=0.15 W=1.2 

.ends

.tran 1n 80u
.control
run 
plot x1_d0 x1_d1 x1_d2 x1_d3 x1_out_v

.endc
.end