Linearity Analysis Tool - Texas Instruments ADS9110EVM-PDK User Manual

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6.6

Linearity Analysis Tool

The linearity analysis tool measures and generates the DNL and INL plots over code for the specific
ADS9110 installed in the evaluation board. It requires a 2-kHz sinusoidal input signal, which is slightly
saturated (35 mV outside full scale range at each input or +0.13 dBFS) with very low distortion. It is critical
for the external source linearity to be better than the ADC linearity. This is important to ensure that the
measured system performance reflects the linearity errors of the ADC and is not 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
Specification Description
External Source Type
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
about 10 µVrms of noise, total number of hits should 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 it is extremely important that the
evaluation board remains undisturbed during the complete duration of the analysis.
SBAU249 – October 2015
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Table 5. External Source Requirements for ADS9110 Evaluation
Signal Frequency
)
S
(R = 2 × R )
S_DIFF S
Amplitude for –0.1 dBFS)
Maximum Noise
Maximum SNR
Maximum THD
Copyright © 2015, Texas Instruments Incorporated
Table 5.
Specification Value
Balanced Differential
0 V or Floating
(Refer to Section 2.2.2
10 Ω–30 Ω
20 Ω–60 Ω
(2 × R × 4.57 × 10
S
(R × 4.57 × 10
S_DIFF
ADS9110EVM-PDK Operation
2 kHz
for jumper settings)
–3
) + 9.14 V
or
–3
) + 9.14 V
30 µV
RMS
100 dB
–130 dB
ADS9110EVM-PDK
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