ATX7006: High performance A/D and D/A converter test system

(conversion) Latency or pipeline delay

The number of clock cycles between initiating a conversion and when de data of the first conversion is present on the output. The data for every sample is available after the pipline delay plus the output delay after the sample is taken.

Conversion time

The time required to do one conversion.

Differential non linearity error (DNL/DNLE)

The maximium deviation of the ideal 1 lsb step. For an ideal DAC the two adjacent digital codes correspond to an output voltage that are exactly 1 LSB apart. A DNLE greater than 1 lsb will lead to a non-monotonic transfer function. See also DA converter parameter calculations - DNL error

End Point and Best Fitting line

See also DAC parameter calculations

Gain error

The difference in output voltage (or current) with a full scale input code and the ideal voltage (or current) at full scale input code (end point calculation). The slope of the reference line is a measure for the gain error. See also DA converter parameter calculations - Gain error

Integral non linearity error (INL/INLE)

Integral non linearity error describes the departure from a reference line. This reference can be an end point line or best fitting line. It is a measure of the straightness of the transfer function and can be greater than the differential non-linearity. The size and distribution of the DNL errors will determine the integral linearity of the converter.

INL is a static specification and relates to THD (a dynamic specification). However, distortion performance can not be predicted from the INL specification, except to say that THD tends to become worse as INL departs from zero. See also DA converter parameter calculations - INL error

Monotonicity

When a DAC is monotonic, the output changes in the same direction (or remains constant) for each increase (or decrease) in input code. So the transfer function of a monotonic device has a slope whose sign does not change.

Multiplying DAC

In a sense, every DAC is a multiplying DAC since the output voltage (or current) is equal to the reference voltage times a constant determined by the digital input code divided by 2n (n is the number of bits of resolution). In a two quadrant multiplying DAC the reference voltage or the digital input code can change the output voltage polarity. If both the reference voltage and the digital code change the output voltage polarity, four quadrant multiplication exists.

Power supply rejection

The sensitivity of a converter to changes in the dc power supply voltages.

Offset Error

The output voltage when the digital input code (mostly 0 or halve scale) is set to give an ideal output voltage of 0 V (end point calculation). For the best fitting line calculation the offset error is the offset of the best fitting reference line related to the ideal transfer line. See also DA converter parameter calculations - Offset error