* SPICE netlist
V1 IN 0 0
V2 -V 0 -5
R2 N001 IN 10K
C1 OUT N001 220p
Q1 N001 0 N002 0 MAT-02
Q2 N003 N004 N002 0 MAT-02
R1 N004 OUT 15.7K
R3 N007 N004 2Meg
R4 N004 0 1K
D1 N007 N005 1N4148
C2 N003 N005 22p
R5 N006 N003 2.5Meg
D2 0 N006 LT1009
R6 +V N006 25K
R7 N002 N005 3K
V3 +V 0 5
B1 Exact 0 V=-Log10(V(in)/10m)
XU1 0 N001 +V -V OUT LTC1050 ;pnba In+)In-)V+)V-)OUT
XU2 0 N003 +V -V N005 LTC1050 ;pnba In+)In-)V+)V-)OUT
.dc dec V1 10u 10 10
+ Cje=82p VJE=.7 MJE=.4 TF=.3n TR=5n Cjc=33p Vjc=.55 Mjc=.5 IKF=.3 PTF=25)

* LTspice schematic (.asc)
Version 4
SHEET 1 1248 480
WIRE -128 -240 -288 -240
WIRE 256 -240 -32 -240
WIRE 336 -240 256 -240
WIRE 496 -240 432 -240
WIRE 256 -224 256 -240
WIRE -80 -160 -80 -176
WIRE 384 -128 384 -176
WIRE 384 -128 48 -128
WIRE 624 -112 624 -128
WIRE -384 -96 -592 -96
WIRE -288 -96 -288 -240
WIRE -288 -96 -304 -96
WIRE -192 -96 -288 -96
WIRE -96 -96 -128 -96
WIRE 256 -96 256 -144
WIRE 416 -96 256 -96
WIRE 496 -96 496 -240
WIRE 496 -96 480 -96
WIRE -592 -80 -592 -96
WIRE -240 -32 -240 -48
WIRE 400 -32 400 -48
WIRE -288 -16 -288 -96
WIRE -272 -16 -288 -16
WIRE 496 -16 496 -96
WIRE 496 -16 432 -16
WIRE 512 -16 496 -16
WIRE 624 -16 624 -32
WIRE 624 -16 592 -16
WIRE -96 0 -96 -96
WIRE -96 0 -208 0
WIRE -64 0 -96 0
WIRE 48 0 48 -128
WIRE 48 0 16 0
WIRE 80 0 48 0
WIRE 176 0 160 0
WIRE 256 0 256 -96
WIRE 256 0 240 0
WIRE 368 0 256 0
WIRE -272 16 -288 16
WIRE 448 16 432 16
WIRE -592 32 -592 0
WIRE 48 32 48 0
WIRE -240 48 -240 32
WIRE 400 48 400 32
WIRE 624 80 624 48
WIRE -336 112 -368 112
WIRE -624 128 -624 112
WIRE -528 128 -528 112
WIRE 48 128 48 112
WIRE -368 144 -368 112
WIRE -96 144 -96 0
WIRE -64 144 -96 144
WIRE -624 240 -624 208
WIRE -528 240 -528 208
WIRE -368 240 -368 224
FLAG -528 240 0
FLAG -240 -48 +V
FLAG -528 112 +V
FLAG -240 48 -V
FLAG -624 240 0
FLAG -624 112 -V
FLAG -592 32 0
FLAG -288 16 0
FLAG -80 -160 0
FLAG 48 128 0
FLAG 400 -48 +V
FLAG 400 48 -V
FLAG 448 16 0
FLAG 624 80 0
FLAG 624 -128 +V
FLAG -592 -96 IN
FLAG -64 144 OUT
FLAG -368 240 0
FLAG -336 112 Exact
SYMBOL voltage -592 -96 R0
SYMATTR InstName V1
SYMATTR Value 0
SYMBOL voltage -624 112 R0
SYMATTR InstName V2
SYMATTR Value -5
SYMBOL res -288 -112 R90
SYMATTR InstName R2
SYMATTR Value 10K
SYMBOL cap -128 -112 R90
SYMATTR InstName C1
SYMATTR Value 220p
SYMBOL npn -128 -176 R270
SYMATTR InstName Q1
SYMATTR Value MAT-02
SYMBOL npn 432 -176 M270
SYMATTR InstName Q2
SYMATTR Value MAT-02
SYMBOL res 32 -16 R90
SYMATTR InstName R1
SYMATTR Value 15.7K
SYMBOL res 176 -16 R90
SYMATTR InstName R3
SYMATTR Value 2Meg
SYMBOL res 32 16 R0
SYMATTR InstName R4
SYMATTR Value 1K
SYMBOL diode 176 16 R270
SYMATTR InstName D1
SYMATTR Value 1N4148
SYMBOL cap 480 -112 R90
SYMATTR InstName C2
SYMATTR Value 22p
SYMBOL res 608 -32 R90
SYMATTR InstName R5
SYMATTR Value 2.5Meg
SYMBOL zener 608 48 M180
SYMATTR InstName D2
SYMATTR Value LT1009
SYMBOL res 608 -128 R0
SYMATTR InstName R6
SYMATTR Value 25K
SYMBOL res 240 -240 R0
SYMATTR InstName R7
SYMATTR Value 3K
SYMBOL voltage -528 112 R0
SYMATTR InstName V3
SYMATTR Value 5
SYMBOL bv -368 128 R0
SYMATTR InstName B1
SYMATTR Value V=-Log10(V(in)/10m)
SYMBOL opamps\\LTC1050A -240 -64 R0
SYMATTR InstName U1
SYMBOL opamps\\LTC1050A 400 -64 M0
SYMATTR InstName U2