REV. 0

AD5334/AD5335/AD5336/AD5344

–9–

TERMINOLOGY

RELATIVE ACCURACY

For the DAC, Relative Accuracy or Integral Nonlinearity (INL)

is a measure of the maximum deviation, in LSBs, from a straight

line passing through the actual endpoints of the DAC transfer

function. Typical INL versus Code plot can be seen in Figures

5, 6, and 7.

DIFFERENTIAL NONLINEARITY

Differential Nonlinearity (DNL) is the difference between the

measured change and the ideal 1 LSB change between any two

adjacent codes. A specified differential nonlinearity of

±1 LSB

maximum ensures monotonicity. This DAC is guaranteed mono-

tonic by design. Typical DNL versus Code plot can be seen in

Figures 8, 9, and 10.

OFFSET ERROR

This is a measure of the offset error of the DAC and the output

amplifier. It is expressed as a percentage of the full-scale range.

If the offset voltage is positive, the output voltage will still be

positive at zero input code. This is shown in Figure 3. Because

the DACs operate from a single supply, a negative offset cannot

appear at the output of the buffer amplifier. Instead, there will

be a code close to zero at which the amplifier output saturates

(amplifier footroom). Below this code there will be a deadband

over which the output voltage will not change. This is illustrated

in Figure 4.

GAIN ERROR

This is a measure of the span error of the DAC (including any

error in the gain of the buffer amplifier). It is the deviation in

slope of the actual DAC transfer characteristic from the ideal

expressed as a percentage of the full-scale range. This is illus-

trated in Figure 2.

OUTPUT

VOLTAGE

DAC CODE

POSITIVE

GAIN ERROR

NEGATIVE

GAIN ERROR

ACTUAL

IDEAL

Figure 2. Gain Error

OUTPUT

VOLTAGE

DAC CODE

POSITIVE

OFFSET

GAIN ERROR

AND

OFFSET

ERROR

ACTUAL

IDEAL

Figure 3. Positive Offset Error and Gain Error

OUTPUT

VOLTAGE

DAC CODE

NEGATIVE

OFFSET

GAIN ERROR

AND

OFFSET

ERROR

AMPLIFIER

FOOTROOM

(~1mV)

NEGATIVE

OFFSET

DEADBAND CODES

ACTUAL

IDEAL

Figure 4. Negative Offset Error and Gain Error