* SPICE netlist
R1 N002 N010 {Ra}
R2 N009 N002 {Rb}
R3 N007 N003 {Rc}
C2 N003 N002 {Cs}
C3 N007 N002 {Cs}
XU2 N009 N007 N001 N012 N003 level1 Avol=1Meg GBW=10Meg Vos=0 En=0 Enk=0 In=0 Ink=0 Rin=500Meg ;pnba In+)In-)V+)V-)OUT
R4 N004 N003 {Ra}
R5 N009 N004 {Rb}
R6 N008 N005 {Rc}
C4 N005 N004 {Cs}
C5 N008 N004 {Cs}
XU3 N009 N008 N001 N012 N005 level1 Avol=1Meg GBW=10Meg Vos=0 En=0 Enk=0 In=0 Ink=0 Rin=500Meg ;pnba In+)In-)V+)V-)OUT
XU4 N005 N006 N001 N012 N011 level1 Avol=1Meg GBW=10Meg Vos=0 En=0 Enk=0 In=0 Ink=0 Rin=500Meg ;pnba In+)In-)V+)V-)OUT
R7 N006 N011 1k
R8 0 N006 1k
V1 N001 N009 5
V2 N009 N012 5
V3 N010 N009 AC 1
.ac lin 40e3 1 20e3
.param Ra 200k
.param Rb 50k
.param Rc 20k
.param Cs 10n

* LTspice schematic (.asc)
Version 4
SHEET 1 1904 640
WIRE -200 -320 -952 -320
WIRE 520 -320 -200 -320
WIRE 840 -320 520 -320
WIRE -952 -288 -952 -320
WIRE -296 -160 -456 -160
WIRE -88 -160 -232 -160
WIRE 424 -160 264 -160
WIRE 632 -160 488 -160
WIRE 952 -144 952 -176
WIRE 952 -64 760 -64
WIRE -312 -48 -344 -48
WIRE -88 -48 -88 -160
WIRE -88 -48 -232 -48
WIRE 408 -48 376 -48
WIRE 632 -48 632 -160
WIRE 632 -48 488 -48
WIRE 952 -48 952 -64
WIRE -200 16 -200 -320
WIRE 520 16 520 -320
WIRE -952 32 -952 -208
WIRE -856 32 -952 32
WIRE -552 32 -648 32
WIRE -456 32 -456 -160
WIRE -456 32 -472 32
WIRE -408 32 -456 32
WIRE -344 32 -344 -48
WIRE -232 32 -344 32
WIRE 264 32 264 -160
WIRE 264 32 248 32
WIRE 312 32 264 32
WIRE 376 32 376 -48
WIRE 488 32 376 32
WIRE 840 32 840 -320
WIRE -88 48 -88 -48
WIRE -88 48 -168 48
WIRE 168 48 168 32
WIRE 168 48 -88 48
WIRE 632 48 632 -48
WIRE 632 48 552 48
WIRE 760 48 760 -64
WIRE 808 48 760 48
WIRE -648 64 -648 32
WIRE -456 64 -456 32
WIRE -232 64 -280 64
WIRE 264 64 264 32
WIRE 488 64 440 64
WIRE 952 64 952 32
WIRE 952 64 872 64
WIRE -952 80 -952 32
WIRE 632 80 632 48
WIRE 808 80 632 80
WIRE -856 192 -856 32
WIRE -648 192 -648 144
WIRE -648 192 -856 192
WIRE -456 192 -456 144
WIRE -456 192 -648 192
WIRE -280 192 -280 64
WIRE -280 192 -456 192
WIRE 264 192 264 144
WIRE 264 192 -280 192
WIRE 440 192 440 64
WIRE 440 192 264 192
WIRE -952 304 -952 160
WIRE -200 304 -200 80
WIRE -200 304 -952 304
WIRE 520 304 520 80
WIRE 520 304 -200 304
WIRE 824 304 520 304
WIRE 840 304 840 96
WIRE 840 304 824 304
WIRE 824 320 824 304
FLAG 952 -176 0
DATAFLAG -144 704 ""
DATAFLAG -144 576 ""
DATAFLAG -144 592 ""
DATAFLAG -144 592 ""
SYMBOL res -456 16 R90
SYMATTR InstName R1
SYMATTR Value {Ra}
SYMBOL res -440 160 R180
SYMATTR InstName R2
SYMATTR Value {Rb}
SYMBOL res -328 -32 R270
SYMATTR InstName R3
SYMATTR Value {Rc}
SYMBOL cap -232 -176 R90
SYMATTR InstName C2
SYMATTR Value {Cs}
SYMBOL cap -344 16 R90
SYMATTR InstName C3
SYMATTR Value {Cs}
SYMBOL OpAmps\\UniversalOpAmp -200 48 R0
SYMATTR InstName U2
SYMBOL res 264 16 R90
SYMATTR InstName R4
SYMATTR Value {Ra}
SYMBOL res 280 160 R180
SYMATTR InstName R5
SYMATTR Value {Rb}
SYMBOL res 392 -32 R270
SYMATTR InstName R6
SYMATTR Value {Rc}
SYMBOL cap 488 -176 R90
SYMATTR InstName C4
SYMATTR Value {Cs}
SYMBOL cap 376 16 R90
SYMATTR InstName C5
SYMATTR Value {Cs}
SYMBOL OpAmps\\UniversalOpAmp 520 48 R0
SYMATTR InstName U3
SYMBOL OpAmps\\UniversalOpAmp 840 64 R0
SYMATTR InstName U4
SYMBOL res 936 -64 R0
SYMATTR InstName R7
SYMATTR Value 1k
SYMBOL res 936 -160 R0
SYMATTR InstName R8
SYMATTR Value 1k
SYMBOL voltage -952 -304 R0
SYMATTR InstName V1
SYMATTR Value 5
SYMBOL voltage -952 64 R0
SYMATTR InstName V2
SYMATTR Value 5
SYMBOL voltage -648 48 R0
SYMATTR InstName V3
SYMATTR Value ""
SYMATTR Value2 AC 1