* SPICE netlist
V1 DAC 0 PULSE(0 2 1m 100m 1m 1m)
V2 N001 0 2048m
M1 N004 N005 N007 N007 IRFH7914
R1 N007 0 100m
V3 N004 0 12 Rser=0.1
XU1 N002 N006 VCC 0 N003 AD8031 ;pnba In+)In-)V+)V-)OUT
R2 N005 N003 100
V4 VCC 0 5
R3 N002 DAC 15k
C1 N003 N006 100p
R4 N003 N002 10Meg
R5 N006 N010 15k
XU2 N008 N011 VCC 0 N010 AD8031 ;pnba In+)In-)V+)V-)OUT
R6 N007 N008 15k
R7 N010 N011 190k
R9 0 N011 10k
R8 N010 N009 1k
C2 N009 0 1n
R10 N010 N011 11
.tran 110m

* LTspice schematic (.asc)
Version 4
SHEET 1 1408 864
WIRE -672 -432 -704 -432
WIRE -416 -432 -528 -432
WIRE -704 -400 -704 -432
WIRE -528 -400 -528 -432
WIRE 112 -352 48 -352
WIRE 224 -352 192 -352
WIRE 704 -352 448 -352
WIRE -704 -288 -704 -320
WIRE -528 -288 -528 -320
WIRE 448 -240 448 -352
WIRE 144 -192 144 -224
WIRE -288 -176 -384 -176
WIRE -80 -176 -288 -176
WIRE 48 -176 48 -352
WIRE 48 -176 0 -176
WIRE 112 -176 48 -176
WIRE 704 -176 704 -352
WIRE 224 -160 224 -352
WIRE 224 -160 176 -160
WIRE 256 -160 224 -160
WIRE 400 -160 336 -160
WIRE 112 -144 48 -144
WIRE -384 -128 -384 -176
WIRE 448 -112 448 -144
WIRE 448 -112 384 -112
WIRE 144 -96 144 -128
WIRE 448 -80 448 -112
WIRE 48 -32 48 -144
WIRE 128 -32 48 -32
WIRE 224 -32 224 -160
WIRE 224 -32 192 -32
WIRE -384 -16 -384 -48
WIRE 48 -16 48 -32
WIRE 224 80 224 48
WIRE 288 96 256 96
WIRE 384 96 384 -112
WIRE 384 96 368 96
WIRE -144 112 -208 112
WIRE 48 112 48 64
WIRE 48 112 -64 112
WIRE 192 112 48 112
WIRE 272 128 256 128
WIRE 448 128 448 0
WIRE 704 128 704 -96
WIRE 704 128 448 128
WIRE -208 144 -208 112
WIRE 48 144 48 112
WIRE 48 144 -48 144
WIRE 448 160 448 128
WIRE -48 176 -48 144
WIRE 48 176 48 144
WIRE 224 176 224 144
WIRE -208 256 -208 208
WIRE -48 288 -48 256
WIRE 48 288 48 256
WIRE 48 288 -48 288
WIRE 272 288 272 128
WIRE 272 288 48 288
WIRE 272 320 272 288
WIRE 272 432 272 400
FLAG -528 -288 0
FLAG -384 -16 0
FLAG -704 -288 0
FLAG -672 -432 VCC
FLAG -288 -176 DAC
FLAG 224 48 0
FLAG 224 176 VCC
FLAG 144 -96 VCC
FLAG 272 432 0
FLAG 448 160 0
FLAG 144 -224 0
FLAG -208 256 0
SYMBOL voltage -384 -144 R0
SYMATTR InstName V1
SYMATTR Value PULSE(0 2 1m 100m 1m 1m)
SYMBOL voltage -528 -416 R0
SYMATTR InstName V2
SYMATTR Value 2048m
SYMBOL nmos 400 -240 R0
SYMATTR InstName M1
SYMATTR Value IRFH7914
SYMBOL res 432 -96 R0
SYMATTR InstName R1
SYMATTR Value 100m
SYMBOL voltage 704 -192 R0
SYMATTR SpiceLine Rser=0.1
SYMATTR InstName V3
SYMATTR Value 12
SYMBOL OpAmps\\AD8032 144 -96 M180
SYMATTR InstName U1
SYMBOL res 352 -176 R90
SYMATTR InstName R2
SYMATTR Value 100
SYMBOL voltage -704 -416 R0
SYMATTR InstName V4
SYMATTR Value 5
SYMBOL res 16 -192 R90
SYMATTR InstName R3
SYMATTR Value 15k
SYMBOL cap 192 -48 R90
SYMATTR InstName C1
SYMATTR Value 100p
SYMBOL res 208 -368 R90
SYMATTR InstName R4
SYMATTR Value 10Meg
SYMBOL res 32 -32 R0
SYMATTR InstName R5
SYMATTR Value 15k
SYMBOL OpAmps\\AD8032 224 176 R180
SYMATTR InstName U2
SYMBOL res 384 80 R90
SYMATTR InstName R6
SYMATTR Value 15k
SYMBOL res 32 160 R0
SYMATTR InstName R7
SYMATTR Value 190k
SYMBOL res 288 416 R180
SYMATTR InstName R9
SYMATTR Value 10k
SYMBOL res -48 96 R90
SYMATTR InstName R8
SYMATTR Value 1k
SYMBOL cap -224 144 R0
SYMATTR InstName C2
SYMATTR Value 1n
SYMBOL res -64 160 R0
SYMATTR InstName R10
SYMATTR Value 11