A 3-Bit A/D Flash Converter

** Circuit Description **

* comparator subcircuit
.subckt comparator  1 2 3
* connections:      | | |
*              output | |
*             +ve input |
*               -ve input           
Iopen1 2 0 0A
Iopen2 3 0 0A
Ecomp 6 0 2 3 1e6
Rout 6 1 10
V+sat 4 0 DC +5V
V-sat 5 0 DC -5V
D1 1 4 ideal_diode
D2 5 1 ideal_diode
.model ideal_diode D (Is=100pA n=0.01)
.ends comparator

** Main Circuit **

* power supplies
Vcc 1 0 DC +5V
Vee 9 0 DC -5V
* input signal source
Vi 11 0 DC 0V
* reference levels for comparators
R1 1 2 10k
R2 2 3 10K
R3 3 4 10k
R4 4 5 10k
R5 5 6 10k
R6 6 7 10k
R7 7 8 10k
R8 8 9 10k
* comparators
Xc1 10 11 2 comparator
Rd1 10 0 1k
Xc2 20 11 3 comparator
Rd2 20 0 1k
Xc3 30 11 4 comparator
Rd3 30 0 1k
Xc4 40 11 5 comparator
Rd4 40 0 1k
Xc5 50 11 6 comparator
Rd5 50 0 1k
Xc6 60 11 7 comparator
Rd6 60 0 1k
Xc7 70 11 8 comparator
Rd7 70 0 1k
** Analysis Requests **
.DC Vi -5V +5V 100mV
** Output Requests **
.PLOT DC V(10) V(20) V(30) V(40) V(50) V(60) V(70)
.probe
.end