* SPICE netlist
V1 N011 0 5
V2 N002 N001 SINE(0 100 1)
R1 N001 N007 500K
R2 N002 N008 500K
R3 N008 N007 22K
I1 N004 0 -.02
R4 N006 0 520
R5 N004 0 330
R6 N004 N006 22K
M1 N004 N005 N006 N006 IRFZ44N
Q1 N005 N010 0 0 2N3904
V3 N003 0 12
V4 N009 0 0
R7 N010 N009 22k
R8 N003 N005 22k
XU1 N007 0 ADR5041 ;pnba 1)2
R9 N011 N007 5K
D1 N008 N011 1N5817
D2 0 N008 1N5817
XU2 N004 0 ADR5045 ;pnba 1)2
R10 0 N008 20Meg
R11 0 N007 20Meg
R12 0 N006 20Meg
.tran 1

* LTspice schematic (.asc)
Version 4
SHEET 1 1904 784
WIRE -664 -392 -712 -392
WIRE -584 -392 -616 -392
WIRE -536 -392 -584 -392
WIRE -712 -312 -712 -392
WIRE -536 -312 -536 -392
WIRE 408 -312 344 -312
WIRE 408 -296 408 -312
WIRE 584 -280 520 -280
WIRE 408 -200 408 -216
WIRE 472 -200 408 -200
WIRE 664 -184 520 -184
WIRE -888 -168 -936 -168
WIRE -712 -168 -712 -232
WIRE -712 -168 -824 -168
WIRE -680 -168 -712 -168
WIRE -536 -168 -536 -232
WIRE -536 -168 -600 -168
WIRE -488 -168 -536 -168
WIRE -424 -168 -488 -168
WIRE -296 -168 -344 -168
WIRE 408 -168 408 -200
WIRE 216 -120 200 -120
WIRE 344 -120 296 -120
WIRE -904 -72 -952 -72
WIRE -824 -72 -824 -168
WIRE 408 -40 408 -72
WIRE -824 8 -824 -72
WIRE 184 56 168 56
WIRE 312 56 248 56
WIRE 408 56 312 56
WIRE 584 56 584 -280
WIRE 584 56 408 56
WIRE 312 72 312 56
WIRE 584 72 584 56
WIRE 408 88 408 56
WIRE -488 104 -488 -168
WIRE -824 120 -824 88
WIRE -488 120 -488 104
WIRE -488 120 -760 120
WIRE 584 168 584 152
WIRE 664 168 664 -184
WIRE 664 168 584 168
WIRE 824 168 664 168
WIRE 952 168 904 168
WIRE 584 184 584 168
WIRE 312 200 312 152
WIRE 408 200 408 168
WIRE -824 280 -824 120
WIRE 584 280 584 264
WIRE -824 392 -824 360
FLAG -824 392 0
FLAG 312 200 0
FLAG 408 200 0
FLAG 584 280 0
FLAG 168 56 0
FLAG 264 -312 0
FLAG 120 -120 0
FLAG 408 -40 0
FLAG -936 -168 0
FLAG -424 104 0
FLAG -296 -168 0
FLAG -952 -72 0
FLAG 952 168 0
SYMBOL voltage -824 264 R0
SYMATTR InstName V1
SYMATTR Value 5
SYMBOL voltage -568 -392 R90
SYMATTR InstName V2
SYMATTR Value SINE(0 100 1)
SYMBOL res -728 -328 R0
SYMATTR InstName R1
SYMATTR Value 500K
SYMBOL res -552 -328 R0
SYMATTR InstName R2
SYMATTR Value 500K
SYMBOL res -584 -184 R90
SYMATTR InstName R3
SYMATTR Value 22K
SYMBOL current 312 72 R0
SYMATTR InstName I1
SYMATTR Value -.02
SYMBOL res 568 168 R0
SYMATTR InstName R4
SYMATTR Value 520
SYMBOL res 392 72 R0
SYMATTR InstName R5
SYMATTR Value 330
SYMBOL res 568 56 R0
SYMATTR InstName R6
SYMATTR Value 22K
SYMBOL nmos 472 -280 R0
SYMATTR InstName M1
SYMATTR Value IRFZ44N
SYMBOL npn 344 -168 R0
SYMATTR InstName Q1
SYMATTR Value 2N3904
SYMBOL voltage 360 -312 R90
SYMATTR Value 12
SYMATTR InstName V3
SYMBOL voltage 216 -120 R90
SYMATTR InstName V4
SYMATTR Value 0
SYMBOL res 312 -136 R90
SYMATTR InstName R7
SYMATTR Value 22k
SYMBOL res 392 -312 R0
SYMATTR InstName R8
SYMATTR Value 22k
SYMBOL References\\ADR5041 -856 -168 R90
SYMATTR InstName U1
SYMBOL res -808 104 R180
SYMATTR InstName R9
SYMATTR Value 5K
SYMBOL schottky -760 104 R90
SYMATTR InstName D1
SYMATTR Value 1N5817
SYMATTR Description Diode
SYMATTR Type diode
SYMBOL schottky -424 88 R90
SYMATTR InstName D2
SYMATTR Value 1N5817
SYMATTR Description Diode
SYMATTR Type diode
SYMBOL References\\ADR5045 216 56 R90
SYMATTR InstName U2
SYMBOL res -328 -184 R90
SYMATTR InstName R10
SYMATTR Value 20Meg
SYMBOL res -920 -56 R270
SYMATTR InstName R11
SYMATTR Value 20Meg
SYMBOL res 920 152 R90
SYMATTR InstName R12
SYMATTR Value 20Meg