Texas Instruments ADS8910B, Руководство пользователя

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ADS8910BEVM-PDK Operation
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22 SBAU268 – July 2016
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ADS8910BEVM-PDK
6.6 Linearity Analysis Tool
The linearity analysis tool measures and generates the DNL and INL plots over code for the specific
ADS8910B installed in the evaluation board. A 2-kHz sinusoidal input signal is required, which is slightly
saturated (35 mV outside the full-scale range at each input or 0.13 dBFS) with very low distortion. The
external source linearity must be better than the ADC linearity. The measured system performance must
reflect the linearity errors of the ADC and must not be limited by the performance of the signal source. To
make sure that the DNL and INL of the ADC are correctly measured, the external source must meet the
requirements in
Table 5 .
Table 5. External Source Requirements for ADS8910B Evaluation
Specification Description Specification Value
Signal frequency 2 kHz
External source type Balanced differential
External source common mode
0 V or floating
(see Section 2.2.2 for jumper settings)
External source impedance (R
S
) 10 Ω –30 Ω
External source differential impedance
(R
S_DIFF
= 2 × R
S
)
20
Ω
–60
Ω
Source differential signal
(V
PP
amplitude for –0.1 dBFS)
(2 × R
S
× 4.57 × 10
–3
) + 9.14 V
or
(R
S_DIFF
× 4.57 × 10
–3
) + 9.14 V
Maximum noise 30 µV
RMS
Maximum SNR 100 dB
Maximum THD –130 dB
The number-of-hits setting depends on the external noise source. For a 110-dB SNR external source with
approximately 10 µVrms of noise, total number of hits must be 512. For a source with 100-dB SNR, the
recommended number of hits is 1024.
NOTE: This analysis can take a couple of minutes to run and the evaluation board must remain
undisturbed during the complete duration of the analysis.