* SPICE netlist
V1 vin 0 PWL REPEAT FOREVER file=senial_fsk.txt ENDREPEAT
V2 vdd 0 5
V3 0 vee 5
R13 vin 0 5
V4 N003 0 PULSE(0 1 0 0.001m 0.001m 10m 20m) AC 1 0
R1 N001 N003 82k
R3 N001 0 100k
C1 N004 N001 6.8n
XU1 0 N004 vdd vee N002 TL081 ;pnba In+)In-)V+)V-)OUT
R4 N002 N004 120k
C2 N002 N001 2.2n
R2 N005 N003 47k
R5 N005 0 82k
C3 N007 N005 4.7n
XU2 0 N007 vdd vee N006 TL081 ;pnba In+)In-)V+)V-)OUT
R6 N006 N007 150k
C4 N006 N005 6.8n
R7 N008 N003 82k
R8 N008 0 100k
C5 N010 N008 6.8n
XU3 0 N010 vdd vee N009 TL081 ;pnba In+)In-)V+)V-)OUT
R9 N009 N010 120k
C6 N009 N008 2.2n
;tran 0 60m 0 10u uic
.include TL081.301
.tran 0 50m 0 10u uic

* LTspice schematic (.asc)
Version 4
SHEET 1 1456 1120
WIRE 472 -544 328 -544
WIRE 728 -544 536 -544
WIRE 56 -496 -152 -496
WIRE -152 -480 -152 -496
WIRE 568 -464 504 -464
WIRE 728 -464 728 -544
WIRE 728 -464 648 -464
WIRE 648 -416 600 -416
WIRE 600 -384 600 -416
WIRE 56 -368 56 -496
WIRE 216 -368 56 -368
WIRE 328 -368 328 -544
WIRE 328 -368 296 -368
WIRE 408 -368 328 -368
WIRE 504 -368 504 -464
WIRE 504 -368 472 -368
WIRE 568 -368 504 -368
WIRE -152 -352 -152 -400
WIRE 728 -352 728 -464
WIRE 728 -352 632 -352
WIRE 328 -336 328 -368
WIRE 568 -336 552 -336
WIRE 600 -320 600 -336
WIRE 600 -288 600 -320
WIRE 648 -288 600 -288
WIRE 552 -240 552 -336
WIRE 328 -208 328 -256
WIRE 472 -160 328 -160
WIRE 728 -160 536 -160
WIRE -472 -80 -568 -80
WIRE -408 -80 -472 -80
WIRE 568 -80 504 -80
WIRE 728 -80 728 -160
WIRE 728 -80 648 -80
WIRE -408 -48 -408 -80
WIRE -568 -32 -568 -80
WIRE 648 -32 600 -32
WIRE 600 0 600 -32
WIRE 56 16 56 -368
WIRE 216 16 56 16
WIRE 328 16 328 -160
WIRE 328 16 296 16
WIRE 408 16 328 16
WIRE 504 16 504 -80
WIRE 504 16 472 16
WIRE 568 16 504 16
WIRE 728 32 728 -80
WIRE 728 32 632 32
WIRE 328 48 328 16
WIRE 568 48 552 48
WIRE -408 64 -408 32
WIRE 600 64 600 48
WIRE 600 96 600 64
WIRE 648 96 600 96
WIRE -648 144 -696 144
WIRE 552 144 552 48
WIRE 328 176 328 128
WIRE -696 192 -696 144
WIRE 472 224 328 224
WIRE 728 224 536 224
WIRE -696 288 -696 272
WIRE -696 288 -728 288
WIRE -696 304 -696 288
WIRE 568 304 504 304
WIRE 728 304 728 224
WIRE 728 304 648 304
WIRE 648 352 600 352
WIRE 600 384 600 352
WIRE 56 400 56 16
WIRE 216 400 56 400
WIRE 328 400 328 224
WIRE 328 400 296 400
WIRE 408 400 328 400
WIRE 504 400 504 304
WIRE 504 400 472 400
WIRE 568 400 504 400
WIRE -696 416 -696 384
WIRE -648 416 -696 416
WIRE 728 416 728 304
WIRE 728 416 632 416
WIRE 328 432 328 400
WIRE 568 432 552 432
WIRE 600 448 600 432
WIRE 600 480 600 448
WIRE 648 480 600 480
WIRE 552 528 552 432
WIRE 328 560 328 512
FLAG -568 48 0
FLAG -472 -80 vin
FLAG -728 288 0
FLAG -648 144 vdd
FLAG -648 416 vee
FLAG -408 64 0
FLAG -152 -352 0
FLAG 328 -208 0
FLAG 552 -240 0
FLAG 648 -416 vdd
FLAG 648 -288 vee
FLAG 328 176 0
FLAG 552 144 0
FLAG 648 -32 vdd
FLAG 648 96 vee
FLAG 328 560 0
FLAG 552 528 0
FLAG 648 352 vdd
FLAG 648 480 vee
SYMBOL voltage -568 -48 R0
SYMATTR Value PWL REPEAT FOREVER file=senial_fsk.txt ENDREPEAT
SYMATTR InstName V1
SYMBOL voltage -696 176 R0
SYMATTR InstName V2
SYMATTR Value 5
SYMBOL voltage -696 288 R0
SYMATTR InstName V3
SYMATTR Value 5
SYMBOL res -424 -64 R0
SYMATTR InstName R13
SYMATTR Value 5
SYMBOL voltage -152 -496 R0
SYMATTR Value2 AC 1 0
SYMATTR Value PULSE(0 1 0 0.001m 0.001m 10m 20m)
SYMATTR InstName V4
SYMBOL res 312 -384 R90
SYMATTR InstName R1
SYMATTR Value 82k
SYMBOL res 312 -352 R0
SYMATTR InstName R3
SYMATTR Value 100k
SYMBOL cap 472 -384 R90
SYMATTR InstName C1
SYMATTR Value 6.8n
SYMBOL Opamps\\opamp2 600 -416 R0
SYMATTR InstName U1
SYMATTR Value TL081
SYMBOL res 664 -480 R90
SYMATTR InstName R4
SYMATTR Value 120k
SYMBOL cap 536 -560 R90
SYMATTR InstName C2
SYMATTR Value 2.2n
SYMBOL res 312 0 R90
SYMATTR InstName R2
SYMATTR Value 47k
SYMBOL res 312 32 R0
SYMATTR InstName R5
SYMATTR Value 82k
SYMBOL cap 472 0 R90
SYMATTR InstName C3
SYMATTR Value 4.7n
SYMBOL Opamps\\opamp2 600 -32 R0
SYMATTR InstName U2
SYMATTR Value TL081
SYMBOL res 664 -96 R90
SYMATTR InstName R6
SYMATTR Value 150k
SYMBOL cap 536 -176 R90
SYMATTR InstName C4
SYMATTR Value 6.8n
SYMBOL res 312 384 R90
SYMATTR InstName R7
SYMATTR Value 82k
SYMBOL res 312 416 R0
SYMATTR InstName R8
SYMATTR Value 100k
SYMBOL cap 472 384 R90
SYMATTR InstName C5
SYMATTR Value 6.8n
SYMBOL Opamps\\opamp2 600 352 R0
SYMATTR InstName U3
SYMATTR Value TL081
SYMBOL res 664 288 R90
SYMATTR InstName R9
SYMATTR Value 120k
SYMBOL cap 536 208 R90
SYMATTR InstName C6
SYMATTR Value 2.2n