* SKY130 3-stage ring oscillator; load=5 fF
.lib /opt/pdk/sky130A/libs.tech/ngspice/sky130.lib.spice tt
.include /opt/pdk/sky130A/libs.ref/sky130_fd_sc_hd/spice/sky130_fd_sc_hd.spice
.param cload=5f
VDD vpwr 0 1.8
X1 n3 0 0 vpwr vpwr n1 sky130_fd_sc_hd__inv_1
X2 n1 0 0 vpwr vpwr n2 sky130_fd_sc_hd__inv_1
X3 n2 0 0 vpwr vpwr n3 sky130_fd_sc_hd__inv_1
C1 n1 0 {cload}
C2 n2 0 {cload}
C3 n3 0 {cload}
.ic v(n1)=0.05 v(n2)=1.75 v(n3)=0.05
.control
set wr_singlescale
set wr_vecnames
tran 2p 30n uic
wrdata /mnt/c/Users/kdong/.codex/visualizations/2026/08/09/019fe405-610d-7b82-826f-09a059483bbd/ringosc-work/results/ringosc_3stage_5ff.csv time v(n1) v(n2) v(n3) i(vdd)
quit
.endc
.end