* SPICE netlist
D1 N008 N006 1N4148
D2 N007 N008 1N4148
R1 N006 signal 10k
R2 N007 N006 10k
XU1 0 N006 12 -12 N008 level2 Avol=1Meg GBW=3Meg Slew=13Meg Ilimit=25m Rail=0 Vos=0 En=0 Enk=0 In=0 Ink=0 Rin=500Meg ;pnba In+)In-)V+)V-)OUT
V1 Signal 0 PULSE(-5 5 0 0.000025 0.000025 0.0001p 0 0)
XU2 0 N009 12 -12 N010 level2 Avol=1Meg GBW=10Meg Slew=10Meg Ilimit=25m Rail=0 Vos=0 En=0 Enk=0 In=0 Ink=0 Rin=500Meg ;pnba In+)In-)V+)V-)OUT
R3 N009 signal 20k
R4 N009 N007 10k
R5 N010 N009 20k
V2 -12 0 -12
V3 12 0 12
D3 N013 N011 BAT54
D4 N012 N013 BAT54
R6 N011 signal 10k
R7 N012 N011 10k
XU3 0 N011 12 -12 N013 level2 Avol=1Meg GBW=16Meg Slew=10Meg Ilimit=25m Rail=0 Vos=0 En=0 Enk=0 In=0 Ink=0 Rin=500Meg ;pnba In+)In-)V+)V-)OUT
XU4 0 N014 12 -12 N015 level2 Avol=1Meg GBW=10Meg Slew=10Meg Ilimit=25m Rail=0 Vos=0 En=0 Enk=0 In=0 Ink=0 Rin=500Meg ;pnba In+)In-)V+)V-)OUT
R8 N014 signal 20k
R9 N014 N012 10k
R10 N015 N014 20k
D5 N003 N001 1N4148
D6 N002 N003 1N4148
R11 N001 signal 10k
R12 N002 N001 10k
XU5 0 N001 12 -12 N003 level2 Avol=1Meg GBW=0.25Meg Slew=0.2Meg Ilimit=25m Rail=0 Vos=0 En=0 Enk=0 In=0 Ink=0 Rin=500Meg ;pnba In+)In-)V+)V-)OUT
XU6 0 N004 12 -12 N005 level2 Avol=1Meg GBW=10Meg Slew=10Meg Ilimit=25m Rail=0 Vos=0 En=0 Enk=0 In=0 Ink=0 Rin=500Meg ;pnba In+)In-)V+)V-)OUT
R13 N004 signal 20k
R14 N004 N002 10k
R15 N005 N004 20k
.tran 0 0.0001 0 1n

* LTspice schematic (.asc)
Version 4
SHEET 1 1904 1504
WIRE 328 -736 232 -736
WIRE 536 -736 408 -736
WIRE 232 -640 232 -736
WIRE 312 -640 232 -640
WIRE 408 -640 376 -640
WIRE 312 -576 296 -576
WIRE 296 -544 296 -576
WIRE 104 -528 88 -528
WIRE 120 -528 104 -528
WIRE 232 -528 232 -640
WIRE 232 -528 200 -528
WIRE 264 -528 232 -528
WIRE 408 -512 408 -640
WIRE 408 -512 328 -512
WIRE 440 -512 408 -512
WIRE 536 -512 536 -736
WIRE 536 -512 504 -512
WIRE 584 -512 536 -512
WIRE 712 -512 664 -512
WIRE 776 -512 712 -512
WIRE 936 -512 856 -512
WIRE 264 -496 232 -496
WIRE 232 -448 232 -496
WIRE 296 -448 296 -480
WIRE 312 -448 296 -448
WIRE 792 -432 776 -432
WIRE 776 -400 776 -432
WIRE 104 -384 104 -528
WIRE 584 -384 104 -384
WIRE 712 -384 712 -512
WIRE 712 -384 664 -384
WIRE 744 -384 712 -384
WIRE 936 -368 936 -512
WIRE 936 -368 808 -368
WIRE 744 -352 712 -352
WIRE 712 -304 712 -352
WIRE 776 -304 776 -336
WIRE 792 -304 776 -304
WIRE 344 -176 248 -176
WIRE 552 -176 424 -176
WIRE 248 -80 248 -176
WIRE 328 -80 248 -80
WIRE 424 -80 392 -80
WIRE 328 -16 312 -16
WIRE 312 16 312 -16
WIRE -920 32 -952 32
WIRE -728 32 -760 32
WIRE -552 32 -584 32
WIRE 120 32 104 32
WIRE 136 32 120 32
WIRE 248 32 248 -80
WIRE 248 32 216 32
WIRE 280 32 248 32
WIRE 424 48 424 -80
WIRE 424 48 344 48
WIRE 456 48 424 48
WIRE 552 48 552 -176
WIRE 552 48 520 48
WIRE 600 48 552 48
WIRE 728 48 680 48
WIRE 792 48 728 48
WIRE 952 48 872 48
WIRE 280 64 248 64
WIRE -952 80 -952 32
WIRE -760 80 -760 32
WIRE -584 80 -584 32
WIRE 248 112 248 64
WIRE 312 112 312 80
WIRE 328 112 312 112
WIRE 808 128 792 128
WIRE 792 160 792 128
WIRE 120 176 120 32
WIRE 600 176 120 176
WIRE 728 176 728 48
WIRE 728 176 680 176
WIRE 760 176 728 176
WIRE -952 192 -952 160
WIRE -760 192 -760 160
WIRE -584 192 -584 160
WIRE 952 192 952 48
WIRE 952 192 824 192
WIRE 760 208 728 208
WIRE 728 256 728 208
WIRE 792 256 792 224
WIRE 808 256 792 256
WIRE 344 320 248 320
WIRE 552 320 424 320
WIRE 248 416 248 320
WIRE 328 416 248 416
WIRE 424 416 392 416
WIRE 328 480 312 480
WIRE 312 512 312 480
WIRE 120 528 104 528
WIRE 136 528 120 528
WIRE 248 528 248 416
WIRE 248 528 216 528
WIRE 280 528 248 528
WIRE 424 544 424 416
WIRE 424 544 344 544
WIRE 456 544 424 544
WIRE 552 544 552 320
WIRE 552 544 520 544
WIRE 600 544 552 544
WIRE 728 544 680 544
WIRE 792 544 728 544
WIRE 952 544 872 544
WIRE 280 560 248 560
WIRE 248 608 248 560
WIRE 312 608 312 576
WIRE 328 608 312 608
WIRE 808 624 792 624
WIRE 792 656 792 624
WIRE 120 672 120 528
WIRE 600 672 120 672
WIRE 728 672 728 544
WIRE 728 672 680 672
WIRE 760 672 728 672
WIRE 952 688 952 544
WIRE 952 688 824 688
WIRE 760 704 728 704
WIRE 728 752 728 704
WIRE 792 752 792 720
WIRE 808 752 792 752
FLAG 248 112 0
FLAG 328 -16 12
IOPIN 176 80 BiDir
FLAG 328 112 -12
IOPIN 176 208 BiDir
FLAG -584 192 0
FLAG -552 32 Signal
IOPIN -704 128 Out
FLAG 104 32 signal
IOPIN -48 128 In
FLAG 728 256 0
FLAG 808 128 12
IOPIN 656 224 BiDir
FLAG 808 256 -12
IOPIN 656 352 BiDir
FLAG -760 192 0
FLAG -952 192 0
FLAG -920 32 12
IOPIN -1072 128 BiDir
FLAG -728 32 -12
IOPIN -880 128 BiDir
FLAG 248 608 0
FLAG 328 480 12
IOPIN 176 576 BiDir
FLAG 328 608 -12
IOPIN 176 704 BiDir
FLAG 104 528 signal
IOPIN -48 624 In
FLAG 728 752 0
FLAG 808 624 12
IOPIN 656 720 BiDir
FLAG 808 752 -12
IOPIN 656 848 BiDir
FLAG 232 -448 0
FLAG 312 -576 12
IOPIN 160 -480 BiDir
FLAG 312 -448 -12
IOPIN 160 -352 BiDir
FLAG 88 -528 signal
IOPIN -64 -432 In
FLAG 712 -304 0
FLAG 792 -432 12
IOPIN 640 -336 BiDir
FLAG 792 -304 -12
IOPIN 640 -208 BiDir
SYMBOL diode 392 -96 R90
SYMATTR InstName D1
SYMATTR Value 1N4148
SYMBOL diode 520 32 R90
SYMATTR InstName D2
SYMATTR Value 1N4148
SYMBOL res 232 16 R90
SYMATTR InstName R1
SYMATTR Value 10k
SYMBOL res 440 -192 R90
SYMATTR InstName R2
SYMATTR Value 10k
SYMBOL Opamps\\UniversalOpamp2 312 48 R0
SYMATTR InstName U1
SYMATTR Value2 Avol=1Meg GBW=3Meg Slew=13Meg
SYMBOL voltage -584 64 R0
SYMATTR InstName V1
SYMATTR Value PULSE(-5 5 0 0.000025 0.000025 0.0001p 0 0)
SYMBOL Opamps\\UniversalOpamp2 792 192 R0
SYMATTR InstName U2
SYMBOL res 696 160 R90
SYMATTR InstName R3
SYMATTR Value 20k
SYMBOL res 696 32 R90
SYMATTR InstName R4
SYMATTR Value 10k
SYMBOL res 888 32 R90
SYMATTR InstName R5
SYMATTR Value 20k
SYMBOL voltage -760 64 R0
SYMATTR InstName V2
SYMATTR Value -12
SYMBOL voltage -952 64 R0
SYMATTR InstName V3
SYMATTR Value 12
SYMBOL schottky 392 400 R90
SYMATTR InstName D3
SYMATTR Value BAT54
SYMATTR Description Diode
SYMATTR Type diode
SYMBOL schottky 520 528 R90
SYMATTR InstName D4
SYMATTR Value BAT54
SYMATTR Description Diode
SYMATTR Type diode
SYMBOL res 232 512 R90
SYMATTR InstName R6
SYMATTR Value 10k
SYMBOL res 440 304 R90
SYMATTR InstName R7
SYMATTR Value 10k
SYMBOL Opamps\\UniversalOpamp2 312 544 R0
SYMATTR InstName U3
SYMATTR Value2 Avol=1Meg GBW=16Meg Slew=10Meg
SYMBOL Opamps\\UniversalOpamp2 792 688 R0
SYMATTR InstName U4
SYMBOL res 696 656 R90
SYMATTR InstName R8
SYMATTR Value 20k
SYMBOL res 696 528 R90
SYMATTR InstName R9
SYMATTR Value 10k
SYMBOL res 888 528 R90
SYMATTR InstName R10
SYMATTR Value 20k
SYMBOL diode 376 -656 R90
SYMATTR InstName D5
SYMATTR Value 1N4148
SYMBOL diode 504 -528 R90
SYMATTR InstName D6
SYMATTR Value 1N4148
SYMBOL res 216 -544 R90
SYMATTR InstName R11
SYMATTR Value 10k
SYMBOL res 424 -752 R90
SYMATTR InstName R12
SYMATTR Value 10k
SYMBOL Opamps\\UniversalOpamp2 296 -512 R0
SYMATTR InstName U5
SYMATTR Value2 Avol=1Meg GBW=0.25Meg Slew=0.2Meg
SYMBOL Opamps\\UniversalOpamp2 776 -368 R0
SYMATTR InstName U6
SYMBOL res 680 -400 R90
SYMATTR InstName R13
SYMATTR Value 20k
SYMBOL res 680 -528 R90
SYMATTR InstName R14
SYMATTR Value 10k
SYMBOL res 872 -528 R90
SYMATTR InstName R15
SYMATTR Value 20k