ADC12DL065

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SNAS249D – MARCH 2005 – REVISED APRIL 2013

Signal Inputs

(3)

for the "A" converter and

(4)

for the "B" converter. Figure 36 shows the expected input signal range. Note that the common mode input

The peaks of the individual input signals should each never exceed 2.6V.

The ADC12DL065 performs best with a differential input signal with each input centered around a common mode

reference voltage or the output data will be clipped.

The two input signals should be exactly 180° out of phase from each other and of the same amplitude. For single

frequency inputs, angular errors result in a reduction of the effective full scale input. For complex waveforms,

however, angular errors will result in distortion.

Figure 36. Expected Input Signal Range

For single frequency sine waves the full scale error in LSB can be described as approximately

(5)

Where dev is the angular difference in degrees between the two signals having a 180° relative phase relationship

to each other (see Figure 37). Drive the analog inputs with a source impedance less than 100

Ω.

Figure 37. Angular Errors Between the Two Input Signals Will Reduce the Output Level or Cause

Distortion

For differential operation, each analog input pin of the differential pair should have a peak-to-peak voltage equal

Single-Ended Operation

Performance with differential input signals is better than with single-ended signals. For this reason, single-ended

operation is not recommended. However, if single ended-operation is required and the resulting performance

degradation is acceptable, one of the analog inputs should be connected to the d.c. mid point voltage of the

driven input. The peak-to-peak differential input signal at the driven input pin should be twice the reference

Because very large input signal swings can degrade distortion performance, better performance with a single-

ended input can be obtained by reducing the reference voltage when maintaining a full-range output. Table 1 and

Table 2 indicate the input to output relationship of the ADC12DL065.

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