* SPICE netlist
V4 Refin 0 {VREF}
C9 0 ADC_out 0.1p
C10 0 ADC_out_dsp 0.1p
V1 VOCM 0 1.5
V2 _DIS 0 3.3
R15 ADC_IN+ FDA_OUT_P 25
R16 ADC_IN- FDA_OUT_N 25
R17 AUXIN+ FDA_OUT_P 100
R18 AUXIN- FDA_OUT_N 100
C15 ADC_IN+ ADC_IN- 39p
C16 AUXIN+ AUXIN- 10p
V_FS1 N006 0 {fs}
V_SEL1 N008 0 {sel}
V_DEC1 N007 0 {decimation}
V6 VS+ 0 5
V7 VS- 0 -5
V14 VDD33 0 3.3
V15 CNV 0 PULSE(0 1.1 {ACQ_delay} 0.2n 0.2n {0.9*(1/fs)} {1/fs})
XU2 N002 FDA_IN+ FDA_IN- N004 VS+ VS- FDA_OUT_N FDA_OUT_P _DIS VOCM VREF 0 0 ADA4945-HP ;pnba 1)2)3)4)5)6)7)8)9)10)11)12)13
R5 N001 N002 {RF}
R6 N005 N004 {RF}
C11 FDA_IN+ N002 {CFilt_2}
C12 FDA_IN- N004 {CFilt_2}
R7 N001 Vin_p {RG}
R8 N005 Vin_n {RG}
C13 N001 0 {CFilt_1}
C14 0 N005 {CFilt_1}
R19 N001 FDA_IN+ {RMFB}
R20 N005 FDA_IN- {RMFB}
Vin_n N003 Vin_n SINE(0 {input_Vpp/4} {input_freq}) AC 0.5 0
Vin_cm N003 0 {input_cm} AC 0
Vin_p Vin_p N003 SINE(0 {input_Vpp/4} {input_freq}) AC 0.5 0
XU1 0 VDD33 Refin ADC_IN+ ADC_IN- AUXIN+ AUXIN- CNV ADC_out ADC_out_dsp N007 N008 N006 ADC_out AD4080 ;pnba GND)Vdd)REFIN)IN+)IN-)AUXIN+)AUXIN-)CNV)Vout)DSPOUT)DEC)SEL)FS)DSPIN
.param VREF=3
.meas NOISE output_noise_rms INTEG V(onoise) FROM 10 TO {Fmax_noise_integration}
.meas NOISE full_scale_sine_rms PARAM 2*VREF/(2*sqrt(2))
.meas NOISE dynamic_range PARAM 20*log10(full_scale_sine_rms/output_noise_rms)
.param Fmax_noise_integration = 1G
.meas NOISE ENOB PARAM (dynamic_range - 1.76)/6.02
.noise V(ADC_out) Vin_p dec 100 10 1G
.param decimation 4
.meas AC ADC_out_max MAX MAG(V(ADC_out))
.meas AC bw_3db FIND frequency WHEN mag(V(ADC_out))=(ADC_out_max/sqrt(2))
.param sel 3
.param input_Vpp=2.966
.param input_freq = 500k
.param input_cm = 0
.param fs = 40MEG
.param ACQ_delay = 10n
.param AFE_gain = 1 ;--> AFE gain = Rf/Rg
.param RF = 499
.param RMFB = 499
.param RG = {RF/AFE_gain}
.param CFilt_1=150p
.param CFilt_2=56p

* LTspice schematic (.asc)
Version 4
SHEET 1 3952 1552
WIRE 984 -776 968 -776
WIRE 1256 -776 1240 -776
WIRE 200 -760 184 -760
WIRE 424 -760 408 -760
WIRE 632 -760 616 -760
WIRE 968 -728 968 -776
WIRE 1240 -728 1240 -776
WIRE 184 -712 184 -760
WIRE 408 -712 408 -760
WIRE 616 -712 616 -760
WIRE 968 -616 968 -648
WIRE 1240 -616 1240 -648
WIRE 184 -600 184 -632
WIRE 408 -600 408 -632
WIRE 616 -600 616 -632
WIRE 1800 -264 1720 -264
WIRE 1880 -264 1800 -264
WIRE 1304 -232 1208 -232
WIRE 1880 -232 1880 -264
WIRE 1304 -216 1304 -232
WIRE -712 -152 -872 -152
WIRE -472 -152 -632 -152
WIRE 1304 -120 1304 -136
WIRE 1880 -120 1880 -152
WIRE -584 -56 -712 -56
WIRE -472 -56 -472 -152
WIRE -472 -56 -520 -56
WIRE 1208 24 1208 -232
WIRE 1560 40 1544 40
WIRE -1720 72 -1768 72
WIRE -1112 72 -1720 72
WIRE -952 72 -1032 72
WIRE -872 72 -872 -152
WIRE -872 72 -952 72
WIRE -824 72 -872 72
WIRE -712 72 -712 -56
WIRE -712 72 -744 72
WIRE -328 72 -408 72
WIRE 1208 72 1208 24
WIRE 600 88 40 88
WIRE 712 88 680 88
WIRE 888 88 712 88
WIRE 984 88 888 88
WIRE -1768 104 -1768 72
WIRE -328 104 -376 104
WIRE 1880 104 1784 104
WIRE 1976 104 1880 104
WIRE -952 120 -952 72
WIRE 1544 120 1544 40
WIRE 1544 120 1512 120
WIRE -328 136 -344 136
WIRE 1880 136 1880 104
WIRE -408 152 -408 72
WIRE -376 152 -376 104
WIRE -344 152 -344 136
WIRE 984 168 984 88
WIRE 1720 168 1720 -264
WIRE 1720 168 1512 168
WIRE -712 184 -712 72
WIRE -584 184 -712 184
WIRE -456 184 -584 184
WIRE -168 184 -280 184
WIRE -40 184 -168 184
WIRE 40 184 40 88
WIRE 40 184 8 184
WIRE 136 184 40 184
WIRE 280 184 216 184
WIRE 888 184 280 184
WIRE 952 184 888 184
WIRE 952 200 952 184
WIRE -472 216 -472 -56
WIRE -456 216 -472 216
WIRE -280 216 -280 184
WIRE 280 216 280 184
WIRE -1768 232 -1768 184
WIRE -1768 232 -1976 232
WIRE -952 232 -952 184
WIRE -952 232 -1000 232
WIRE 712 232 712 88
WIRE 1880 232 1880 200
WIRE -1000 248 -1000 232
WIRE -584 248 -712 248
WIRE -456 248 -584 248
WIRE -1976 264 -1976 232
WIRE -1768 264 -1768 232
WIRE 1544 264 1512 264
WIRE 1784 264 1784 104
WIRE 1784 264 1544 264
WIRE -952 280 -952 232
WIRE -456 280 -472 280
WIRE -456 312 -504 312
WIRE -280 312 -280 280
WIRE -168 312 -280 312
WIRE -40 312 8 184
WIRE -40 312 -168 312
WIRE 8 312 -40 184
WIRE 40 312 8 312
WIRE 136 312 40 312
WIRE 280 312 280 280
WIRE 280 312 216 312
WIRE 888 312 280 312
WIRE 952 312 952 232
WIRE 952 312 888 312
WIRE 1544 312 1544 264
WIRE 1544 312 1512 312
WIRE 1880 344 1512 344
WIRE 1960 344 1880 344
WIRE -504 360 -504 312
WIRE -344 360 -344 344
WIRE 1880 376 1880 344
WIRE -1976 392 -1976 344
WIRE -1768 392 -1768 344
WIRE -1720 392 -1768 392
WIRE -1112 392 -1720 392
WIRE -952 392 -952 344
WIRE -952 392 -1032 392
WIRE -872 392 -952 392
WIRE -824 392 -872 392
WIRE -712 392 -712 248
WIRE -712 392 -744 392
WIRE 1112 392 1112 360
WIRE -376 408 -376 344
WIRE -360 408 -376 408
WIRE 40 408 40 312
WIRE 600 408 40 408
WIRE 712 408 712 296
WIRE 712 408 680 408
WIRE 888 408 712 408
WIRE 984 408 984 264
WIRE 984 408 888 408
WIRE -408 440 -408 344
WIRE -360 440 -408 440
WIRE 1880 472 1880 440
WIRE -712 520 -712 392
WIRE -584 520 -712 520
WIRE -472 520 -472 280
WIRE -472 520 -520 520
WIRE -872 600 -872 392
WIRE -696 600 -872 600
WIRE -472 600 -472 520
WIRE -472 600 -616 600
WIRE 1208 632 1208 360
WIRE 1208 632 1112 632
WIRE 1336 632 1336 360
WIRE 1432 632 1336 632
WIRE 1112 680 1112 632
WIRE 1272 680 1272 360
WIRE 1432 680 1432 632
WIRE 1112 776 1112 760
WIRE 1272 776 1272 760
WIRE 1432 776 1432 760
FLAG 1304 -120 0
FLAG 1112 392 0
FLAG 1880 232 0
FLAG 1880 472 0
FLAG 1976 104 ADC_out
FLAG 1960 344 ADC_out_dsp
FLAG 968 -616 0
FLAG 984 -776 VOCM
FLAG 1240 -616 0
FLAG 1256 -776 _DIS
FLAG 888 88 AUXIN+
FLAG 888 184 ADC_IN+
FLAG 888 312 ADC_IN-
FLAG 888 408 AUXIN-
FLAG 1112 776 0
FLAG 1272 776 0
FLAG 1432 776 0
FLAG 184 -600 0
FLAG 408 -600 0
FLAG 200 -760 VS+
FLAG 424 -760 VS-
FLAG 616 -600 0
FLAG 632 -760 VDD33
FLAG 1880 -120 0
FLAG 1800 -264 CNV
FLAG 1560 40 VDD33
FLAG 1208 24 Refin
FLAG -328 104 VOCM
FLAG -328 72 VS+
FLAG -360 440 VS-
FLAG -504 360 0
FLAG -360 408 _DIS
FLAG -584 184 FDA_IN+
FLAG -584 248 FDA_IN-
FLAG -344 360 0
FLAG -328 136 VREF
FLAG -168 184 FDA_OUT_N
FLAG -168 312 FDA_OUT_P
FLAG -1976 392 0
FLAG -1720 72 Vin_p
FLAG -1720 392 Vin_n
FLAG -1000 248 0
SYMBOL voltage 1304 -232 R0
SYMATTR InstName V4
SYMATTR Value {VREF}
SYMBOL cap 1864 200 M180
SYMATTR InstName C9
SYMATTR Value 0.1p
SYMBOL cap 1864 440 M180
SYMATTR InstName C10
SYMATTR Value 0.1p
SYMBOL voltage 968 -744 R0
SYMATTR InstName V1
SYMATTR Value 1.5
SYMBOL voltage 1240 -744 R0
SYMATTR InstName V2
SYMATTR Value 3.3
SYMBOL res 232 168 R90
SYMATTR InstName R15
SYMATTR Value 25
SYMBOL res 232 296 R90
SYMATTR InstName R16
SYMATTR Value 25
SYMBOL res 696 72 R90
SYMATTR InstName R17
SYMATTR Value 100
SYMBOL res 696 392 R90
SYMATTR InstName R18
SYMATTR Value 100
SYMBOL cap 264 216 R0
SYMATTR InstName C15
SYMATTR Value 39p
SYMBOL cap 696 232 R0
SYMATTR InstName C16
SYMATTR Value 10p
SYMBOL voltage 1112 664 M0
SYMATTR InstName V_FS1
SYMATTR Value {fs}
SYMBOL voltage 1272 664 M0
SYMATTR InstName V_SEL1
SYMATTR Value {sel}
SYMBOL voltage 1432 664 M0
SYMATTR InstName V_DEC1
SYMATTR Value {decimation}
SYMBOL voltage 184 -728 R0
SYMATTR InstName V6
SYMATTR Value 5
SYMBOL voltage 408 -728 R0
SYMATTR InstName V7
SYMATTR Value -5
SYMBOL voltage 616 -728 R0
SYMATTR InstName V14
SYMATTR Value 3.3
SYMBOL voltage 1880 -248 R0
SYMATTR Value PULSE(0 1.1 {ACQ_delay} 0.2n 0.2n {0.9*(1/fs)} {1/fs})
SYMATTR InstName V15
SYMBOL OpAmps\\ADA4945-HP -408 248 R0
SYMATTR InstName U2
SYMBOL res -728 -136 R270
SYMATTR InstName R5
SYMATTR Value {RF}
SYMBOL res -712 616 R270
SYMATTR InstName R6
SYMATTR Value {RF}
SYMBOL cap -584 -40 R270
SYMATTR Value {CFilt_2}
SYMATTR InstName C11
SYMBOL cap -584 536 R270
SYMATTR Value {CFilt_2}
SYMATTR InstName C12
SYMBOL res -1016 56 R90
SYMATTR InstName R7
SYMATTR Value {RG}
SYMBOL res -1016 376 R90
SYMATTR InstName R8
SYMATTR Value {RG}
SYMBOL cap -968 120 R0
SYMATTR Value {CFilt_1}
SYMATTR InstName C13
SYMBOL cap -968 280 R0
SYMATTR Value {CFilt_1}
SYMATTR InstName C14
SYMBOL res -840 88 R270
SYMATTR InstName R19
SYMATTR Value {RMFB}
SYMBOL res -840 408 R270
SYMATTR InstName R20
SYMATTR Value {RMFB}
SYMBOL voltage -1768 248 R0
SYMATTR Value2 AC 0.5 0
SYMATTR Value SINE(0 {input_Vpp/4} {input_freq})
SYMATTR InstName Vin_n
SYMBOL voltage -1976 248 R0
SYMATTR Value2 AC 0
SYMATTR InstName Vin_cm
SYMATTR Value {input_cm}
SYMBOL voltage -1768 88 R0
SYMATTR Value2 AC 0.5 0
SYMATTR Value SINE(0 {input_Vpp/4} {input_freq})
SYMATTR InstName Vin_p
SYMBOL ADC\\AD4080 1208 216 R0
SYMATTR InstName U1