Version 4
SHEET 1 1564 680
WIRE 1120 -32 928 -32
WIRE 928 16 928 -32
WIRE 224 32 176 32
WIRE 528 32 480 32
WIRE 224 48 224 32
WIRE 528 48 528 32
WIRE 96 96 96 32
WIRE 112 96 96 96
WIRE 176 96 176 32
WIRE 176 96 160 96
WIRE 400 96 400 32
WIRE 416 96 400 96
WIRE 480 96 480 32
WIRE 480 96 464 96
WIRE 1168 96 1040 96
WIRE 1296 96 1232 96
WIRE 112 112 112 96
WIRE 160 112 160 96
WIRE 416 112 416 96
WIRE 464 112 464 96
WIRE 928 144 928 96
WIRE 96 160 48 160
WIRE 208 160 176 160
WIRE 400 160 352 160
WIRE 512 160 480 160
WIRE 1040 176 1040 96
WIRE 1168 176 1040 176
WIRE 1296 176 1296 96
WIRE 1296 176 1248 176
WIRE 1120 240 1120 -32
WIRE -208 256 -240 256
WIRE -128 256 -208 256
WIRE 48 256 48 160
WIRE 48 256 -48 256
WIRE 352 256 352 160
WIRE 352 256 48 256
WIRE 1040 256 1040 176
WIRE 1040 256 896 256
WIRE 1088 256 1040 256
WIRE 816 272 816 256
WIRE 816 272 256 272
WIRE 1296 272 1296 176
WIRE 1296 272 1152 272
WIRE 1392 272 1360 272
WIRE 1488 272 1392 272
WIRE 1088 288 1040 288
WIRE -208 304 -208 256
WIRE 208 304 208 160
WIRE 256 304 256 272
WIRE 256 304 208 304
WIRE 288 304 256 304
WIRE 512 304 512 160
WIRE 560 304 512 304
WIRE 592 304 560 304
WIRE 1392 304 1392 272
WIRE 1040 320 1040 288
WIRE 1040 320 992 320
WIRE 560 336 560 304
WIRE 912 336 912 320
WIRE 912 336 560 336
WIRE 512 352 512 304
WIRE 208 368 208 304
WIRE 912 400 880 400
WIRE 1120 400 1120 304
WIRE 1120 400 976 400
WIRE 1120 432 1120 400
WIRE 1392 432 1392 384
WIRE -208 448 -208 384
WIRE 208 448 208 432
WIRE 512 448 512 416
FLAG 224 48 0
FLAG -208 448 0
FLAG 208 448 0
FLAG 288 304 A1
IOPIN 288 304 Out
FLAG 528 48 0
FLAG 512 448 0
FLAG 592 304 A2
IOPIN 592 304 Out
FLAG 1120 432 0
FLAG 928 144 0
FLAG 1488 272 Q
IOPIN 1488 272 Out
FLAG 1392 432 0
FLAG -240 256 Inp
IOPIN -240 256 In
SYMBOL sw 192 160 R90
SYMATTR InstName S1
SYMATTR Value MYSW
SYMBOL voltage 80 32 R270
WINDOW 0 -32 56 VBottom 2
WINDOW 3 104 57 VTop 2
WINDOW 123 0 0 Left 0
WINDOW 39 0 0 Left 0
SYMATTR InstName V1
SYMATTR Value PULSE(-1 1 0 10n 10n {t} {4*t})
SYMBOL res -32 240 R90
WINDOW 0 0 56 VBottom 2
WINDOW 3 32 56 VTop 2
SYMATTR InstName R1
SYMATTR Value 50
SYMBOL voltage -208 288 R0
WINDOW 123 0 0 Left 0
WINDOW 39 24 124 Left 2
SYMATTR InstName V2
SYMATTR Value SINE(1.5V 10m 139k)
SYMBOL cap 192 368 R0
SYMATTR InstName C1
SYMATTR Value {cap}
SYMBOL sw 496 160 R90
SYMATTR InstName S2
SYMATTR Value MYSW
SYMBOL voltage 384 32 R270
WINDOW 0 -32 56 VBottom 2
WINDOW 3 59 66 VTop 2
WINDOW 123 0 0 Left 0
WINDOW 39 0 0 Left 0
SYMATTR InstName V3
SYMATTR Value PULSE(-1 1 {2*t} 10n 10n {t} {4*t})
SYMBOL cap 496 352 R0
SYMATTR InstName C2
SYMATTR Value {cap}
SYMBOL Opamps\\LT6231 1120 272 R0
SYMATTR InstName U1
SYMBOL res 912 240 R90
WINDOW 0 0 56 VBottom 2
WINDOW 3 32 56 VTop 2
SYMATTR InstName R4
SYMATTR Value 100
SYMBOL res 1008 304 R90
WINDOW 0 0 56 VBottom 2
WINDOW 3 32 56 VTop 2
SYMATTR InstName R5
SYMATTR Value 100
SYMBOL res 1264 160 R90
WINDOW 0 0 56 VBottom 2
WINDOW 3 32 56 VTop 2
SYMATTR InstName R6
SYMATTR Value 10k
SYMBOL cap 1232 80 R90
WINDOW 0 0 32 VBottom 2
WINDOW 3 32 32 VTop 2
SYMATTR InstName C3
SYMATTR Value {cap2}
SYMBOL voltage 928 0 R0
WINDOW 123 0 0 Left 0
WINDOW 39 0 0 Left 0
SYMATTR InstName V4
SYMATTR Value 3.3V
SYMBOL cap 1360 256 R90
WINDOW 0 0 32 VBottom 2
WINDOW 3 32 32 VTop 2
SYMATTR InstName C4
SYMATTR Value 10µF
SYMBOL res 1376 288 R0
SYMATTR InstName R3
SYMATTR Value 1k
SYMBOL res 896 384 R90
WINDOW 0 0 56 VBottom 2
WINDOW 3 32 56 VTop 2
SYMATTR InstName R2
SYMATTR Value 100
SYMBOL cap 976 384 R90
WINDOW 0 0 32 VBottom 2
WINDOW 3 32 32 VTop 2
SYMATTR InstName C5
SYMATTR Value 10µ
TEXT -624 -48 Left 2 !.model MYSW SW(Ron 5; Roff; 1Meg; vt=0; Vh=0 )
TEXT -792 -80 Left 2 !.tran 0 110m 109m
TEXT -488 24 Left 2 ;QSD  3.2019
TEXT -896 176 Left 2 !.param t=1/clock
TEXT -896 96 Left 2 !;.param clock=406k
TEXT -888 128 Left 2 !.param clock=326k
TEXT -896 16 Left 2 !.param cap=33n
TEXT -560 88 Left 2 ;FFT :\nBlackman-Harris four-term window
TEXT -896 48 Left 2 !.param cap2=330p