Other Parts Discussed in Thread: INA823,
Hi， team！
I want to calculate ADC823+ Amp8689 error.
offset voltage error:
INA823: G=1, V(OS_RTI)=V_OSI+V_OSO∕G=(20+140∕1)uV=160.06uV V(OS_INA)=G*V(OS_RTI)=160.06uV
ADS8689: V(OS_ADC)=Eo=±0.2mV
V_OST=√((V(OS_INA))^2+(V(OS_ADC))^2 )≈256.16uV
Gain Error:
E_G=√((E(INA_G))^2+(E(ADC_G)^2+(E_R1)^2 ) R1 is sample resistor(50ohm,0.1% )
= √(0.01^2*2+0.1^2)
≈0.101%
Noise:
INA823: En_ina=√((e(nr ) )^2+(e(ni ) )^2+(e_nv ) )^2 )≈153.48uV(Resistor Noise/Current Noise/Voltage Noise)
ADS8689: V(FSR_rms)=0.5∙FSR∙0.707≈7239.68mV
E(n_adc)=V(FSR_rms)/(10^(SNR/20)) =7239.68mV/(10^(91.5dB/20)) ≈192.63uV
E(n_total)=√((E(n_ina))^2+(E_(n_adc))^2 )≈246.30uV
I want to know if there is something wrong in the above formula?
And I want to calculate total error(Etotal) ,including offset error, gain error and noise error.
Can I calculate like this?
E_total=√((V_OST/Vin )^2+E_G^2+(E(n_total)/Vin )^2 )=???
Is this formula right? And Vin is -10V~+10V, so I choose 2.5Vref as shown in figure.
E_total=√((V_OST/Vin )^2+E_G^2+(E(n_total)/Vin )^2 )=√((256.16uV/10V)^2+0.101%^2+(246.30uV/10)^2)=???%
I think there is something wrong and it's too small. Could you tell me which formula is wrong?
Thank you so much!
