*SPICE circuit from XCircuit v3.10 .subckt nor Y A B M1 ext14 A Vdd Vdd pmos M2 Y A GND GND nmos M3 Y B GND GND nmos M4 Y B ext14 Vdd pmos .ends .subckt half_ff ext5 ext2 ext3 X1 ext2 ext5 ext3 nor .ends X2 S !Q Q half_ff X3 R Q !Q half_ff .ends X4 SRflipflop .end