.subckt ND1 a b z vdd vdds gnd gnds ds=1
Xpmos1 vdd a z  vdds pt_st w=2*ds*Awd#
Xpmos2 vdd b z  vdds pt_st w=2*ds*Awd#
Xnmos1 st  a z  gnds nt_cd w=2*ds*Awd#
Xnmos2 gnd b st gnds nt_cs w=2*ds*Awd#
.ends

.subckt ND4 a b z vdd vdds gnd gnds ds=4
Xpmos1 vdd a z  vdds pt_st w=2*ds*Awd#
Xpmos2 vdd b z  vdds pt_st w=2*ds*Awd#
Xnmos1 st  a z  gnds nt_cd w=2*ds*Awd#
Xnmos2 gnd b st gnds nt_cs w=2*ds*Awd#
.ends