* SPICE netlist
R1 Vref r7 2k
R2 r7 r6 220
R3 r6 r5 220
R4 r5 r4 220
R5 r4 r3 220
R6 r3 r2 220
R7 r2 r1 220
A1 0 N001 0 0 0 0 7 0 XOR
A2 N001 N002 0 0 0 0 6 0 XOR
A3 N002 N003 0 0 0 0 5 0 XOR
A4 N003 N004 0 0 0 0 4 0 XOR
A5 N004 N005 0 0 0 0 3 0 XOR
A6 N005 N006 0 0 0 0 2 0 XOR
A7 N006 N007 0 0 0 0 1 0 XOR
V1 Vsig 0 PULSE(0 2.5 0 .1m 10n 10n .1m)
R11 r1 0 220
V2 Vref 0 5
V3 v1 0 5
A8 0 7 5 3 1 0 a0 0 OR
A9 0 7 6 3 2 0 a1 0 OR
A10 0 7 6 5 4 0 a2 0 OR
A11 Vsig r7 0 0 0 0 N001 0 SCHMITT Vt=0 vh=.1m tripdt=1n
A12 Vsig r6 0 0 0 0 N002 0 SCHMITT Vt=0 vh=.1m tripdt=1n
A13 Vsig r5 0 0 0 0 N003 0 SCHMITT Vt=0 vh=.1m tripdt=1n
A14 Vsig r4 0 0 0 0 N004 0 SCHMITT Vt=0 vh=.1m tripdt=1n
A15 Vsig r3 0 0 0 0 N005 0 SCHMITT Vt=0 vh=.1m tripdt=1n
A16 Vsig r2 0 0 0 0 N006 0 SCHMITT Vt=0 vh=.1m tripdt=1n
A17 Vsig r1 0 0 0 0 N007 0 SCHMITT Vt=0 vh=.1m tripdt=1n
.tran 0 0.2m 0 .1u
.options plotwinsize=0

* LTspice schematic (.asc)
Version 4
SHEET 1 1296 1312
WIRE -616 -640 -648 -640
WIRE -104 -640 -616 -640
WIRE 312 -608 264 -608
WIRE 424 -608 376 -608
WIRE 312 -560 296 -560
WIRE -376 -544 -488 -544
WIRE -248 -544 -296 -544
WIRE -184 -544 -248 -544
WIRE 8 -544 -184 -544
WIRE 264 -528 264 -608
WIRE 264 -528 72 -528
WIRE 296 -528 296 -560
WIRE -648 -512 -648 -640
WIRE -488 -512 -488 -544
WIRE -104 -512 -104 -640
WIRE 8 -512 -104 -512
WIRE -248 -496 -248 -544
WIRE 264 -448 264 -528
WIRE 312 -448 264 -448
WIRE 312 -432 264 -432
WIRE 424 -432 376 -432
WIRE -648 -400 -648 -432
WIRE -488 -400 -488 -432
WIRE -248 -368 -248 -416
WIRE -184 -368 -248 -368
WIRE 8 -368 -184 -368
WIRE -248 -352 -248 -368
WIRE 264 -352 264 -432
WIRE 264 -352 72 -352
WIRE -104 -336 -104 -512
WIRE 8 -336 -104 -336
WIRE 264 -272 264 -352
WIRE 312 -272 264 -272
WIRE 312 -256 264 -256
WIRE 424 -256 376 -256
WIRE 536 -208 488 -208
WIRE 648 -208 600 -208
WIRE -248 -192 -248 -272
WIRE -184 -192 -248 -192
WIRE 8 -192 -184 -192
WIRE 536 -192 504 -192
WIRE -456 -176 -456 -208
WIRE 264 -176 264 -256
WIRE 264 -176 72 -176
WIRE 536 -176 488 -176
WIRE -104 -160 -104 -336
WIRE 8 -160 -104 -160
WIRE 536 -160 504 -160
WIRE -248 -144 -248 -192
WIRE 264 -96 264 -176
WIRE 312 -96 264 -96
WIRE 536 -96 488 -96
WIRE 648 -96 600 -96
WIRE 312 -80 264 -80
WIRE 424 -80 376 -80
WIRE 536 -80 504 -80
WIRE -456 -64 -456 -96
WIRE 536 -64 488 -64
WIRE 536 -48 504 -48
WIRE -248 -16 -248 -64
WIRE -184 -16 -248 -16
WIRE 8 -16 -184 -16
WIRE 264 0 264 -80
WIRE 264 0 72 0
WIRE -104 16 -104 -160
WIRE 8 16 -104 16
WIRE 536 16 488 16
WIRE 648 16 600 16
WIRE -248 32 -248 -16
WIRE 536 32 504 32
WIRE 536 48 488 48
WIRE 536 64 504 64
WIRE 264 80 264 0
WIRE 312 80 264 80
WIRE 312 96 264 96
WIRE 424 96 376 96
WIRE -248 160 -248 112
WIRE -184 160 -248 160
WIRE 8 160 -184 160
WIRE 264 176 264 96
WIRE 264 176 72 176
WIRE -104 192 -104 16
WIRE 8 192 -104 192
WIRE -248 208 -248 160
WIRE 264 256 264 176
WIRE 312 256 264 256
WIRE 312 272 264 272
WIRE 424 272 376 272
WIRE -248 336 -248 288
WIRE -184 336 -248 336
WIRE 8 336 -184 336
WIRE 264 352 264 272
WIRE 264 352 72 352
WIRE -104 368 -104 192
WIRE 8 368 -104 368
WIRE -248 384 -248 336
WIRE 264 432 264 352
WIRE 312 432 264 432
WIRE 312 448 264 448
WIRE 424 448 376 448
WIRE -248 512 -248 464
WIRE -184 512 -248 512
WIRE 8 512 -184 512
WIRE -248 528 -248 512
WIRE 264 528 264 448
WIRE 264 528 72 528
WIRE -104 544 -104 368
WIRE 8 544 -104 544
WIRE -248 656 -248 608
FLAG -248 656 0
FLAG -648 -400 0
FLAG -488 -400 0
FLAG -456 -208 v1
IOPIN -304 32 In
FLAG -456 -64 0
FLAG 296 -528 0
FLAG -616 -640 Vsig
FLAG -488 -544 Vref
FLAG 424 448 1
FLAG 424 272 2
FLAG 424 96 3
FLAG 424 -80 4
FLAG 424 -256 5
FLAG 424 -432 6
FLAG 424 -608 7
FLAG 488 48 3
FLAG 504 32 5
FLAG 488 16 7
FLAG 504 64 1
FLAG 488 -64 3
FLAG 504 -80 6
FLAG 488 -96 7
FLAG 504 -48 2
FLAG 488 -176 5
FLAG 504 -192 6
FLAG 488 -208 7
FLAG 504 -160 4
FLAG 648 16 a0
FLAG 648 -96 a1
FLAG 648 -208 a2
FLAG -184 -544 r7
FLAG -184 -368 r6
FLAG -184 -192 r5
FLAG -184 -16 r4
FLAG -184 160 r3
FLAG -184 336 r2
FLAG -184 512 r1
SYMBOL res -392 -528 R270
SYMATTR InstName R1
SYMATTR Value 2k
SYMBOL res -264 -512 R0
SYMATTR InstName R2
SYMATTR Value 220
SYMBOL res -264 -368 R0
SYMATTR InstName R3
SYMATTR Value 220
SYMBOL res -264 -160 R0
SYMATTR InstName R4
SYMATTR Value 220
SYMBOL res -264 16 R0
SYMATTR InstName R5
SYMATTR Value 220
SYMBOL res -264 192 R0
SYMATTR InstName R6
SYMATTR Value 220
SYMBOL res -264 368 R0
SYMATTR InstName R7
SYMATTR Value 220
SYMBOL Digital\\xor 360 -656 R0
SYMATTR InstName A1
SYMBOL Digital\\xor 360 -480 R0
SYMATTR InstName A2
SYMBOL Digital\\xor 360 -304 R0
SYMATTR InstName A3
SYMBOL Digital\\xor 360 -128 R0
SYMATTR InstName A4
SYMBOL Digital\\xor 360 48 R0
SYMATTR InstName A5
SYMBOL Digital\\xor 360 224 R0
SYMATTR InstName A6
SYMBOL Digital\\xor 360 400 R0
SYMATTR InstName A7
SYMBOL voltage -648 -528 R0
SYMATTR Value PULSE(0 2.5 0 .1m 10n 10n .1m)
SYMATTR InstName V1
SYMBOL res -264 512 R0
SYMATTR InstName R11
SYMATTR Value 220
SYMBOL voltage -488 -528 R0
SYMATTR InstName V2
SYMATTR Value 5
SYMBOL voltage -456 -192 R0
SYMATTR InstName V3
SYMATTR Value 5
SYMBOL Digital\\or 568 -32 R0
SYMATTR InstName A8
SYMBOL Digital\\or 568 -144 R0
SYMATTR InstName A9
SYMBOL Digital\\or 568 -256 R0
SYMATTR InstName A10
SYMBOL Digital\\diffschmtbuf 8 -464 M180
SYMATTR InstName A11
SYMATTR Value Vt=0 vh=.1m
SYMATTR Value2 tripdt=1n
SYMBOL Digital\\diffschmtbuf 8 -288 M180
SYMATTR InstName A12
SYMATTR Value Vt=0 vh=.1m
SYMATTR Value2 tripdt=1n
SYMBOL Digital\\diffschmtbuf 8 -112 M180
SYMATTR InstName A13
SYMATTR Value Vt=0 vh=.1m
SYMATTR Value2 tripdt=1n
SYMBOL Digital\\diffschmtbuf 8 64 M180
SYMATTR InstName A14
SYMATTR Value Vt=0 vh=.1m
SYMATTR Value2 tripdt=1n
SYMBOL Digital\\diffschmtbuf 8 240 M180
SYMATTR InstName A15
SYMATTR Value Vt=0 vh=.1m
SYMATTR Value2 tripdt=1n
SYMBOL Digital\\diffschmtbuf 8 416 M180
SYMATTR InstName A16
SYMATTR Value Vt=0 vh=.1m
SYMATTR Value2 tripdt=1n
SYMBOL Digital\\diffschmtbuf 8 592 M180
SYMATTR InstName A17
SYMATTR Value Vt=0 vh=.1m
SYMATTR Value2 tripdt=1n