ADC10D040

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SNAS149G – OCT 2001 – REVISED MARCH 2013

Figure 4. AC Test Circuit

Specification Definitions

APERTURE (SAMPLING) DELAY is that time required after the fall of the clock input for the sampling switch to

the clock goes low.

APERTURE JITTER is the variation in aperture delay from sample to sample. Aperture jitter shows up as input

noise.

CLOCK DUTY CYCLE is the ratio of the time that the clock waveform is high to the total time of one clock

period.

CROSSTALK is coupling of energy from one channel into the other channel.

DIFFERENTIAL NON-LINEARITY (DNL) is the measure of the maximum deviation from the ideal step size of 1

LSB. Measured at 40 MSPS with a ramp input.

EFFECTIVE NUMBER OF BITS (ENOB, or EFFECTIVE BITS) is another method of specifying Signal-to-Noise

and Distortion Ratio, or SINAD. ENOB is defined as (SINAD

− 1.76)/6.02 and says that the converter is

equivalent to a perfect ADC of this (ENOB) number of bits.

FULL POWER BANDWIDTH (FPBW) is the frequency at which the magnitude of the reconstructed output

fundamental drops 3 dB below its 1 MHz value.

GAIN ERROR is the difference between the ideal and actual differences between the input levels at which the

first and last code transitions occur. That is, how far this difference is from Full Scale.

INTEGRAL NON LINEARITY (INL) is a measure of the maximum deviation of each individual code from a line

drawn from negative full scale (½ LSB below the first code transition) through positive full scale (½ LSB above

the last code transition). The deviation of any given code from this straight line is measured from the center of

that code value. The end point test method is used. Measured at 40 MSPS with a ramp input.

INTERMODULATION DISTORTION (IMD) is the creation of spectral components that are not present in the

input as a result of two sinusoidal frequencies being applied to the ADC input at the same time. It is defined as

the ratio of the power in the second and third order intermodulation products to the total power in one of the

original frequencies. IMD is usually expressed in dB.

LSB (LEAST SIGNIFICANT BIT) is the bit that has the smallest value of weight of all bits. This value is

n

(1)

where “m” is the reference scale factor and “n” is the ADC resolution, which is 10 in the case of the ADC10D040.

The value of “m” is determined by the logic level at the gain pin and has a value of 1 when the gain pin is at a

logic low and a value of 2 when the gain pin is at a logic high.

MISSING CODES are those output codes that are skipped and will never appear at the ADC outputs. These

codes cannot be reached with any input value.

MSB (MOST SIGNIFICANT BIT) is the bit that has the largest value or weight. Its value is one half of full scale.

OFFSET ERROR is a measure of how far the mid-scale transition point is from the ideal zero voltage input.

OUTPUT DELAY is the time delay after the rising edge of the input clock before the data update is present at the

output pins.

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