Linearity Analysis Tool - Texas Instruments ADS8900BEVM-PDK User Manual

ADS8900BEVM-PDK Operation
6.6

Linearity Analysis Tool

The linearity analysis tool measures and generates the DNL and INL plots over code for the specific
ADS8900B 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
Specification Description
External source common mode
External source impedance (R
External source differential impedance
Source differential signal
(V
PP
The number-of-hits setting depends on the external noise source. For a 110-dB SNR external source with
approximately 10 µVrms of noise, the 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.
22
ADS8900BEVM-PDK
5.
Table 5. External Source Requirements for ADS8900B Evaluation
Signal frequency
External source type
)
S
(R = 2 × R )
S_DIFF S
amplitude for –0.1 dBFS)
Maximum noise
Maximum SNR
Maximum THD
Copyright © 2016, Texas Instruments Incorporated
Specification Value
2 kHz
Balanced differential
0 V or floating
(see Section 2.2.2 for jumper settings)
10 Ω–30 Ω
20 Ω–60 Ω
–3
(2 × R × 4.57 × 10 ) + 9.14 V
S
or
–3
(R × 4.57 × 10 ) + 9.14 V
S_DIFF
30 µV
RMS
100 dB
–130 dB
SBAU269 – October 2016
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