* SPICE netlist
M1 N002 N008 N009 N004 PMOS
M2 N009 N001 N002 N005 PMOS
M3 N014 N011 N009 N012 PMOS
M4 N002 N001 N010 N006 PMOS
M5 N010 N003 N002 N007 PMOS
M6 N010 N014 N011 N013 PMOS
M7 N014 N008 N018 N015 NMOS
M8 N018 N001 0 N021 NMOS
M9 0 N011 N014 N019 NMOS
M10 N011 N014 0 N016 NMOS
M11 N020 N003 N011 N017 NMOS
M12 0 N001 N020 N022 NMOS
V1 N002 0 5
V2 N008 0 PULSE(0 5 0.5n 1n 1n 4m 8m)
V3 N001 0 PULSE(0 5 0.5n 1n 1n 4m 8m)
V4 N003 0 PULSE(0 5 0.5n 1n 1n 8m 16m)
.tran 16m

* LTspice schematic (.asc)
Version 4
SHEET 1 1392 880
WIRE 696 -440 -8 -440
WIRE -328 -408 -696 -408
WIRE 280 -408 -328 -408
WIRE -328 -328 -328 -408
WIRE -328 -328 -440 -328
WIRE -168 -328 -328 -328
WIRE 280 -328 280 -408
WIRE 280 -328 152 -328
WIRE 376 -328 280 -328
WIRE -8 -312 -8 -440
WIRE -8 -312 -120 -312
WIRE 104 -312 -8 -312
WIRE 600 -312 424 -312
WIRE -440 -280 -440 -312
WIRE -168 -280 -168 -312
WIRE 152 -280 152 -312
WIRE 376 -280 376 -312
WIRE -696 -264 -696 -408
WIRE -488 -248 -600 -248
WIRE 104 -248 104 -312
WIRE -328 -232 -440 -232
WIRE -168 -232 -328 -232
WIRE 280 -232 152 -232
WIRE 376 -232 280 -232
WIRE -328 -136 -328 -232
WIRE 280 -136 280 -232
WIRE -280 -120 -296 -120
WIRE -120 -120 -280 -120
WIRE -328 -88 -328 -120
WIRE 280 -88 280 -120
WIRE 232 -56 88 -56
WIRE -120 -24 -120 -120
WIRE 264 -24 -120 -24
WIRE 280 -24 280 -40
WIRE 280 -24 264 -24
WIRE -328 -8 -328 -40
WIRE 88 -8 88 -56
WIRE 88 -8 -328 -8
WIRE -328 40 -328 -8
WIRE -328 40 -440 40
WIRE -216 40 -328 40
WIRE 264 40 264 -24
WIRE 264 40 168 40
WIRE 392 40 264 40
WIRE -440 88 -440 40
WIRE 168 104 168 40
WIRE 392 104 392 40
WIRE 600 120 600 -312
WIRE 600 120 440 120
WIRE -216 152 -216 40
WIRE -600 168 -600 -248
WIRE -488 168 -600 168
WIRE -440 168 -440 136
WIRE -120 168 -120 -24
WIRE -120 168 -168 168
WIRE -600 184 -600 168
WIRE 88 184 88 -8
WIRE 120 184 88 184
WIRE 168 184 168 152
WIRE 392 184 392 152
WIRE -440 232 -440 184
WIRE -216 232 -216 200
WIRE 392 248 392 200
WIRE 600 264 600 120
WIRE -552 312 -632 312
WIRE -488 312 -552 312
WIRE -440 312 -440 280
WIRE 392 328 392 296
WIRE -632 344 -632 312
WIRE -440 360 -440 328
WIRE -328 360 -440 360
WIRE -216 360 -216 248
WIRE -216 360 -328 360
WIRE 168 360 168 200
WIRE 264 360 168 360
WIRE 392 360 392 344
WIRE 392 360 264 360
WIRE -552 440 -552 312
WIRE 440 440 440 264
WIRE 440 440 -552 440
WIRE 696 440 696 -440
WIRE 696 440 440 440
FLAG -328 360 0
FLAG 264 360 0
FLAG -696 -184 0
FLAG -600 264 0
FLAG -632 424 0
FLAG 600 344 0
SYMBOL pmos4 -488 -328 R0
SYMATTR InstName M1
SYMBOL pmos4 -120 -232 R180
SYMATTR InstName M2
SYMBOL pmos4 -280 -40 R180
SYMATTR InstName M3
SYMBOL pmos4 104 -328 R0
SYMATTR InstName M4
SYMBOL pmos4 424 -232 R180
SYMATTR InstName M5
SYMBOL pmos4 232 -136 R0
SYMATTR InstName M6
SYMBOL nmos4 -488 88 R0
SYMATTR InstName M7
SYMBOL nmos4 -488 232 R0
SYMATTR InstName M8
SYMBOL nmos4 -168 248 R180
SYMATTR InstName M9
SYMBOL nmos4 120 104 R0
SYMATTR InstName M10
SYMBOL nmos4 440 200 R180
SYMATTR InstName M11
SYMBOL nmos4 440 344 R180
SYMATTR InstName M12
SYMBOL voltage -696 -280 R0
SYMATTR InstName V1
SYMATTR Value 5
SYMBOL voltage -600 168 R0
SYMATTR Value PULSE(0 5 0.5n 1n 1n 4m 8m)
SYMATTR InstName V2
SYMBOL voltage -632 328 R0
SYMATTR Value PULSE(0 5 0.5n 1n 1n 4m 8m)
SYMATTR InstName V3
SYMBOL voltage 600 248 R0
SYMATTR InstName V4
SYMATTR Value PULSE(0 5 0.5n 1n 1n 8m 16m)