* SPICE netlist
V1 12 0 12
V2 0 -12 12
R4 N007 N006 10k
C2 N007 0 {C}
V4 N006 0 PULSE(0 5 0 100n 100n 0u 10u) AC 1
R5 N001 N003 10k
R6 N002 N001 20k
XU4 0 N001 12 -12 N002 LT1498 ;pnba In+)In-)V+)V-)OUT
XU2 N007 N003 12 -12 N003 LT1498 ;pnba In+)In-)V+)V-)OUT
R7 N011 N010 10k
C3 N011 0 {C}
V5 N010 0 PULSE(0 5 0 100n 100n 5u 10u) AC 1
XU5 N011 N008 12 -12 N009 LT1498 ;pnba In+)In-)V+)V-)OUT
R10 N008 0 10k
R11 N009 N008 10k
R13 N004 N002 10k
R14 N004 N009 10k
XU3 0 N004 12 -12 N005 LT1498 ;pnba In+)In-)V+)V-)OUT
R15 N005 N004 10k
C5 N009 N008 {C}
C1 N002 N001 {C}
C4 N005 N004 {C}
.tran 10m startup
.param C=15n

* LTspice schematic (.asc)
Version 4.1
SHEET 1 1392 560
WIRE 216 -264 184 -264
WIRE 296 -264 280 -264
WIRE 184 -184 184 -264
WIRE 200 -184 184 -184
WIRE 296 -184 296 -264
WIRE 296 -184 280 -184
WIRE 72 -168 -56 -168
WIRE 568 -120 520 -120
WIRE 664 -120 632 -120
WIRE -56 -104 -56 -168
WIRE -24 -104 -56 -104
WIRE -264 -88 -344 -88
WIRE -152 -88 -184 -88
WIRE -72 -88 -152 -88
WIRE 72 -88 72 -168
WIRE 72 -88 40 -88
WIRE 88 -88 72 -88
WIRE 184 -88 184 -184
WIRE 184 -88 168 -88
WIRE 200 -88 184 -88
WIRE -344 -72 -344 -88
WIRE -152 -72 -152 -88
WIRE -72 -72 -72 -88
WIRE -24 -72 -72 -72
WIRE 296 -72 296 -184
WIRE 296 -72 264 -72
WIRE 344 -72 296 -72
WIRE 200 -56 184 -56
WIRE 520 -24 520 -120
WIRE 552 -24 520 -24
WIRE 664 -24 664 -120
WIRE 664 -24 632 -24
WIRE -24 24 -56 24
WIRE 72 24 40 24
WIRE 344 24 344 -72
WIRE 392 24 344 24
WIRE -680 72 -680 56
WIRE -680 72 -696 72
WIRE 472 72 472 24
WIRE 520 72 520 -24
WIRE 520 72 472 72
WIRE 552 72 520 72
WIRE -680 88 -680 72
WIRE 664 88 664 -24
WIRE 664 88 616 88
WIRE 696 88 664 88
WIRE -56 104 -56 24
WIRE -40 104 -56 104
WIRE 72 104 72 24
WIRE 72 104 40 104
WIRE 552 104 536 104
WIRE 392 120 344 120
WIRE 472 120 472 72
WIRE -56 168 -56 104
WIRE -24 168 -56 168
WIRE -264 184 -344 184
WIRE -152 184 -184 184
WIRE -72 184 -152 184
WIRE 72 184 72 104
WIRE 72 184 40 184
WIRE 344 184 344 120
WIRE 344 184 72 184
WIRE -344 200 -344 184
WIRE -152 200 -152 184
WIRE -72 200 -72 184
WIRE -24 200 -72 200
FLAG -696 72 0
FLAG -680 168 -12
FLAG -680 -24 12
FLAG 232 -40 -12
FLAG 232 -104 12
FLAG 184 -56 0
FLAG -152 -8 0
FLAG -344 8 0
FLAG 8 -56 -12
FLAG 8 -120 12
FLAG -152 264 0
FLAG -344 280 0
FLAG 8 216 -12
FLAG 8 152 12
FLAG -136 104 0
FLAG 584 120 -12
FLAG 584 56 12
FLAG 536 104 0
SYMBOL voltage -680 -40 R0
SYMATTR InstName V1
SYMATTR Value 12
SYMBOL voltage -680 72 R0
SYMATTR InstName V2
SYMATTR Value 12
SYMBOL res -168 -104 R90
SYMATTR InstName R4
SYMATTR Value 10k
SYMBOL cap -168 -72 R0
SYMATTR InstName C2
SYMATTR Value {C}
SYMBOL voltage -344 -88 R0
SYMATTR Value PULSE(0 5 0 100n 100n 0u 10u)
SYMATTR Value2 AC 1
SYMATTR InstName V4
SYMBOL res 184 -104 R90
SYMATTR InstName R5
SYMATTR Value 10k
SYMBOL res 296 -200 R90
SYMATTR InstName R6
SYMATTR Value 20k
SYMBOL OpAmps\\RH1498 232 -136 R0
SYMATTR InstName U4
SYMBOL OpAmps\\RH1498 8 -152 R0
SYMATTR InstName U2
SYMBOL res -168 168 R90
SYMATTR InstName R7
SYMATTR Value 10k
SYMBOL cap -168 200 R0
SYMATTR InstName C3
SYMATTR Value {C}
SYMBOL voltage -344 184 R0
SYMATTR Value PULSE(0 5 0 100n 100n 5u 10u)
SYMATTR Value2 AC 1
SYMATTR InstName V5
SYMBOL OpAmps\\RH1498 8 120 R0
SYMATTR InstName U5
SYMBOL res -40 88 R90
SYMATTR InstName R10
SYMATTR Value 10k
SYMBOL res 56 88 R90
SYMATTR InstName R11
SYMATTR Value 10k
SYMBOL res 488 8 R90
SYMATTR InstName R13
SYMATTR Value 10k
SYMBOL res 488 104 R90
SYMATTR InstName R14
SYMATTR Value 10k
SYMBOL OpAmps\\RH1498 584 24 R0
SYMATTR InstName U3
SYMBOL res 648 -40 R90
SYMATTR InstName R15
SYMATTR Value 10k
SYMBOL cap 40 8 R90
SYMATTR InstName C5
SYMATTR Value {C}
SYMBOL cap 280 -280 R90
SYMATTR InstName C1
SYMATTR Value {C}
SYMBOL cap 632 -136 R90
SYMATTR InstName C4
SYMATTR Value {C}