* SPICE netlist
VSupply Batt_Supply 0 6.6
XU1 3V_Reference 3V_OpAmp_Prefilter_Voltage Batt_Supply 0 3V_OpAmp_Prefilter_Voltage level1 Avol=1Meg GBW=10Meg Vos=0 En=0 Enk=0 In=0 Ink=0 Rin=500Meg ;pnba In+)In-)V+)V-)OUT
R1 3V_OpAmp_Prefilter_Voltage 0 2G
L_Filter1 3V_Output_Voltage 3V_OpAmp_Prefilter_Voltage 100n
C_Filter1 3V_Output_Voltage 0 1pico
R_Filter1 3V_Output_Voltage 0 1Mega
I1 3V_Output_Voltage 0 PULSE(0 .2 .75 .001 .01 0.25)
XU2 3.3V_Reference N002 Batt_Supply 0 N002 level1 Avol=1Meg GBW=10Meg Vos=0 En=0 Enk=0 In=0 Ink=0 Rin=500Meg ;pnba In+)In-)V+)V-)OUT
XU3 5V_Reference N001 Batt_Supply 0 N001 level1 Avol=1Meg GBW=10Meg Vos=0 En=0 Enk=0 In=0 Ink=0 Rin=500Meg ;pnba In+)In-)V+)V-)OUT
L_Filter2 3.3V_Output_Voltage N002 100n
L_Filter3 5V_Output_Voltage N001 100n
C_Filter2 3.3V_Output_Voltage 0 1pico
C_Filter3 5V_Output_Voltage 0 1pico
R_Filter3 5V_Output_Voltage 0 1Mega
R_Filter2 3.3V_Output_Voltage 0 1Mega
I2 3.3V_Output_Voltage 0 PULSE(0 .5 .25 .01 .001 0.66)
I3 5V_Output_Voltage 0 PULSE(0 .5 .5 .001 .001 1)
R2 N002 0 2G
R3 N001 0 2G
R5 5V_Reference 3.3V_Reference 1.7Mega
R6 3.3V_Reference 3V_Reference 0.3Mega
R7 3V_Reference 0 3Mega
R8 Batt_Supply 5V_Reference 6.6Kilo
D1 0 5V_Reference UMZ5_1N
;op
;tran 2
.dc Supply 7.4 6

* LTspice schematic (.asc)
Version 4
SHEET 1 1344 1232
WIRE -512 -616 -576 -616
WIRE -512 -472 -512 -616
WIRE -512 -360 -512 -392
WIRE -512 -360 -672 -360
WIRE -672 -328 -672 -360
WIRE 64 -328 -304 -328
WIRE -144 -296 -160 -296
WIRE 64 -264 64 -328
WIRE 464 -264 448 -264
WIRE 32 -248 -32 -248
WIRE 112 -232 96 -232
WIRE 144 -232 112 -232
WIRE 256 -232 224 -232
WIRE 352 -232 256 -232
WIRE 448 -232 448 -264
WIRE 448 -232 352 -232
WIRE 672 -232 448 -232
WIRE -512 -216 -512 -360
WIRE -160 -216 -160 -296
WIRE -160 -216 -512 -216
WIRE 32 -216 -160 -216
WIRE 352 -184 352 -232
WIRE 672 -184 672 -232
WIRE 256 -168 256 -232
WIRE -32 -152 -32 -248
WIRE 112 -152 112 -232
WIRE 112 -152 -32 -152
WIRE 64 -72 64 -200
WIRE 256 -72 256 -104
WIRE 352 -72 352 -104
WIRE 672 -72 672 -120
WIRE -304 8 -304 -328
WIRE 64 8 -304 8
WIRE -512 24 -512 -216
WIRE -144 40 -160 40
WIRE 64 72 64 8
WIRE 464 72 448 72
WIRE 32 88 -32 88
WIRE 112 104 96 104
WIRE 144 104 112 104
WIRE 256 104 224 104
WIRE 352 104 256 104
WIRE 448 104 448 72
WIRE 448 104 352 104
WIRE 672 104 448 104
WIRE -512 120 -512 104
WIRE -160 120 -160 40
WIRE -160 120 -512 120
WIRE 32 120 -160 120
WIRE 352 152 352 104
WIRE 672 152 672 104
WIRE 256 168 256 104
WIRE -32 184 -32 88
WIRE 112 184 112 104
WIRE 112 184 -32 184
WIRE 64 264 64 136
WIRE 256 264 256 232
WIRE 352 264 352 232
WIRE 672 264 672 216
WIRE -304 328 -304 8
WIRE -288 328 -304 328
WIRE 144 328 128 328
WIRE -512 360 -512 120
WIRE -304 360 -304 328
WIRE 64 360 -304 360
WIRE -144 392 -160 392
WIRE 64 408 64 360
WIRE 464 408 448 408
WIRE 32 424 -32 424
WIRE 128 440 128 328
WIRE 128 440 96 440
WIRE 160 440 128 440
WIRE 272 440 240 440
WIRE 352 440 272 440
WIRE 448 440 448 408
WIRE 448 440 352 440
WIRE 672 440 448 440
WIRE -512 456 -512 440
WIRE -160 456 -160 392
WIRE -160 456 -512 456
WIRE 32 456 -160 456
WIRE -576 472 -576 -616
WIRE -304 472 -304 360
WIRE -304 472 -576 472
WIRE -512 488 -512 456
WIRE 352 488 352 440
WIRE -304 504 -304 472
WIRE -32 504 -32 424
WIRE 128 504 128 440
WIRE 128 504 -32 504
WIRE 272 504 272 440
WIRE 672 504 672 440
WIRE -32 520 -32 504
WIRE -672 616 -672 -264
WIRE -512 616 -512 568
WIRE -304 616 -304 584
WIRE -32 616 -32 600
WIRE 64 616 64 472
WIRE 272 616 272 568
WIRE 352 616 352 568
WIRE 672 616 672 568
FLAG -304 616 0
FLAG 64 616 0
FLAG -32 616 0
FLAG 272 616 0
FLAG 352 616 0
FLAG 464 408 3V_Output_Voltage
FLAG 144 328 3V_OpAmp_Prefilter_Voltage
FLAG -288 328 Batt_Supply
FLAG -144 392 3V_Reference
FLAG 672 616 0
FLAG 256 -72 0
FLAG 256 264 0
FLAG 352 264 0
FLAG 352 -72 0
FLAG 672 264 0
FLAG 672 -72 0
FLAG 64 -72 0
FLAG 64 264 0
FLAG -32 -72 0
FLAG -32 264 0
FLAG -512 616 0
FLAG -144 40 3.3V_Reference
FLAG -144 -296 5V_Reference
FLAG 464 72 3.3V_Output_Voltage
FLAG 464 -264 5V_Output_Voltage
FLAG -672 616 0
SYMBOL voltage -304 488 R0
SYMATTR InstName Supply
SYMATTR Value 6.6
SYMBOL OpAmps\\UniversalOpAmp 64 440 R0
SYMATTR InstName U1
SYMBOL res -48 504 R0
SYMATTR InstName R1
SYMATTR Value 2G
SYMBOL ind 256 424 R90
SYMATTR InstName L_Filter1
SYMATTR Value 100n
SYMBOL cap 256 504 R0
SYMATTR InstName C_Filter1
SYMATTR Value 1pico
SYMBOL res 336 472 R0
SYMATTR InstName R_Filter1
SYMATTR Value 1Mega
SYMBOL load 656 504 R0
SYMATTR InstName I1
SYMATTR Value PULSE(0 .2 .75 .001 .01 0.25)
SYMBOL OpAmps\\UniversalOpAmp 64 104 R0
SYMATTR InstName U2
SYMBOL OpAmps\\UniversalOpAmp 64 -232 R0
SYMATTR InstName U3
SYMBOL ind 240 88 R90
SYMATTR InstName L_Filter2
SYMATTR Value 100n
SYMBOL ind 240 -248 R90
SYMATTR InstName L_Filter3
SYMATTR Value 100n
SYMBOL cap 240 168 R0
SYMATTR InstName C_Filter2
SYMATTR Value 1pico
SYMBOL cap 240 -168 R0
SYMATTR InstName C_Filter3
SYMATTR Value 1pico
SYMBOL res 336 -200 R0
SYMATTR InstName R_Filter3
SYMATTR Value 1Mega
SYMBOL res 336 136 R0
SYMATTR InstName R_Filter2
SYMATTR Value 1Mega
SYMBOL load 656 152 R0
SYMATTR InstName I2
SYMATTR Value PULSE(0 .5 .25 .01 .001 0.66)
SYMBOL load 656 -184 R0
SYMATTR InstName I3
SYMATTR Value PULSE(0 .5 .5 .001 .001 1)
SYMBOL res -48 168 R0
SYMATTR InstName R2
SYMATTR Value 2G
SYMBOL res -48 -168 R0
SYMATTR InstName R3
SYMATTR Value 2G
SYMBOL res -528 8 R0
SYMATTR InstName R5
SYMATTR Value 1.7Mega
SYMBOL res -528 344 R0
SYMATTR InstName R6
SYMATTR Value 0.3Mega
SYMBOL res -528 472 R0
SYMATTR InstName R7
SYMATTR Value 3Mega
SYMBOL res -528 -488 R0
SYMATTR InstName R8
SYMATTR Value 6.6Kilo
SYMBOL zener -656 -264 R180
SYMATTR InstName D1
SYMATTR Value UMZ5_1N