Version 4
SHEET 1 880 680
WIRE 112 -208 0 -208
WIRE 176 -208 112 -208
WIRE 272 -208 240 -208
WIRE 336 -208 272 -208
WIRE 448 -208 416 -208
WIRE 112 -176 112 -208
WIRE -352 -160 -352 -176
WIRE -240 -160 -240 -176
WIRE 496 -144 368 -144
WIRE 432 -80 432 -96
WIRE -352 -64 -352 -80
WIRE -240 -64 -240 -80
WIRE 112 -64 112 -96
WIRE 368 -64 368 -144
WIRE 368 -64 112 -64
WIRE 400 -64 368 -64
WIRE 0 -48 0 -208
WIRE 496 -48 496 -144
WIRE 496 -48 464 -48
WIRE 272 -32 272 -208
WIRE 400 -32 272 -32
WIRE 432 0 432 -16
WIRE -304 64 -352 64
WIRE -256 64 -304 64
WIRE -144 64 -176 64
WIRE -112 64 -144 64
WIRE 0 64 0 16
WIRE 0 64 -32 64
WIRE 32 64 0 64
WIRE 160 64 112 64
WIRE 192 64 160 64
WIRE 304 64 272 64
WIRE -352 112 -352 64
WIRE 224 208 224 192
WIRE -352 224 -352 192
WIRE 160 224 160 64
WIRE 192 224 160 224
WIRE 304 240 304 64
WIRE 304 240 256 240
WIRE 368 240 304 240
WIRE -144 256 -144 64
WIRE 192 256 -144 256
WIRE 224 288 224 272
FLAG -352 224 0
FLAG 448 -208 0
FLAG -304 64 in
FLAG 368 240 out
IOPIN 368 240 Out
FLAG 224 192 V+
FLAG 224 288 V-
FLAG 432 -96 V+
FLAG 432 0 V-
FLAG -352 -176 V+
FLAG -352 -64 0
FLAG -240 -176 V-
FLAG -240 -64 0
SYMBOL cap -16 -48 R0
SYMATTR InstName C1
SYMATTR Value 22n
SYMBOL cap 176 -192 R270
WINDOW 0 32 32 VTop 2
WINDOW 3 0 32 VBottom 2
SYMATTR InstName C2
SYMATTR Value 4.7n
SYMBOL voltage -352 96 R0
SYMATTR InstName V1
SYMATTR Value AC 1
SYMBOL Opamps\\LT1212 224 176 R0
SYMATTR InstName U1
SYMBOL Opamps\\LT1212 432 -112 R0
SYMATTR InstName U2
SYMBOL voltage -352 -176 R0
SYMATTR InstName V2
SYMATTR Value 15
SYMBOL voltage -240 -176 R0
SYMATTR InstName V3
SYMATTR Value -15
SYMBOL Misc\\EuropeanResistor 96 -192 R0
SYMATTR InstName R3
SYMATTR Value 1k
SYMBOL Misc\\EuropeanResistor -272 80 R270
WINDOW 0 27 56 VTop 2
WINDOW 3 5 56 VBottom 2
SYMATTR InstName R1
SYMATTR Value 10k
SYMBOL Misc\\EuropeanResistor -128 80 R270
WINDOW 0 27 56 VTop 2
WINDOW 3 5 56 VBottom 2
SYMATTR InstName RPa
SYMATTR Value {X*10k}
SYMBOL Misc\\EuropeanResistor 16 80 R270
WINDOW 0 27 56 VTop 2
WINDOW 3 5 56 VBottom 2
SYMATTR InstName RPb
SYMATTR Value {10k*(1-X)}
SYMBOL Misc\\EuropeanResistor 176 80 R270
WINDOW 0 27 56 VTop 2
WINDOW 3 5 56 VBottom 2
SYMATTR InstName R2
SYMATTR Value 10k
SYMBOL Misc\\EuropeanResistor 320 -192 R270
WINDOW 0 27 56 VTop 2
WINDOW 3 5 56 VBottom 2
SYMATTR InstName R4
SYMATTR Value 47k
TEXT -360 -360 Left 2 !.ac dec 200 100 10k
TEXT -360 -320 Left 2 !.step param X list 0.01 0.5 0.99