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EVAL-AD7903SDZ User Guide

UG-609

Rev. 0 | Page 17 of 32

GENERATING A HISTOGRAM OF THE ADC CODE

DISTRIBUTION

The Histogram tab can be used to perform ac testing or, more

commonly, dc testing. This tab shows the ADC code distribution of

the input and computes the mean and standard deviation, which are

displayed as DC Offset/Mean and Transition Noise, respectively,

in the Histogram Analysis area (located toward the bottom of

the window).

Figure 23 shows the histogram with ac input for a 1 kHz sine

wave applied to the ADC input and the resulting calculations.

AC Input

To perform a histogram test of ac input,

1. Apply a differential sinusoidal signal with low distortion

(better than 100 dB) to the evaluation board at the J6/J7 or

J10/J15 input SMA connector pair.

2. Click the Histogram tab from the main window.

3. Click Single Capture or Continuous Capture.

Raw data is then captured and passed to the PC for statistical

computations, and various measured values are displayed in the

Histogram Analysis area.

DC Input

A histogram test of dc input can be performed with or without

an external source because the evaluation board has a buffered

VREF/2 source at the ADC input.

To perform a histogram test of dc input,

1. If an external source is being used, apply a differential

sinusoidal signal with low distortion (better than 100 dB)

to the evaluation board at the J6/J7 or J10/J15 input SMA

connector pair. It may be required to filter the signal to ensure

that the dc source is noise-compatible with the ADC.

2. Click the Histogram tab from the main window.

3. Click Single Capture or Continuous Capture.

Raw data is then captured and passed to the PC for statistical

computations, and various measured values are displayed in the

Histogram Analysis area.

Figure 23. Histogram Tab

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