ADC12DL066

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SNAS188F – MAY 2004 – REVISED FEBRUARY 2008

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.

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

and Distortion 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 is a measure of the frequency at which the reconstructed output fundamental

drops 3 dB below its low frequency value for a full scale input.

GAIN ERROR (G.E.) is the deviation from the ideal slope of the transfer function. It can be calculated as:

G.E. = Pos. Full-Scale Error

− Neg. Full-Scale Error

(6)

Gain Error can also be separated into Positive Gain Error (PGE) and Negative Gain Error (NGE), which are.

PGE = Pos. Full-Scale Error

− Offset Error

(7)

NGE = Offset Error

− Neg. Full-Scale Error

(8)

GAIN ERROR MATCHING is the difference in gain errors between the two converters divided by the average

gain of the converters.

INTEGRAL NON LINEARITY (INL) is a measure of the 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.

INTERMODULATION DISTORTION (IMD) is the creation of additional spectral components 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 intermodulation products to the total power in the original frequencies. IMD is usually expressed in dBFS.

where “n” is the ADC resolution in bits, which is 12 in the case of the ADC12DL066.

MISSING CODES are those output codes that will never appear at the ADC outputs. The ADC12DL066 is

guaranteed not to have any missing codes.

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

NEGATIVE FULL SCALE ERROR is the difference between the actual first code transition and its ideal value of

½ LSB above negative full scale.

from code 2047 to 2048.

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

output pins.

input range to a specified voltage within the normal input range and the converter makes a conversion with its

rated accuracy.

PIPELINE DELAY (LATENCY) See CONVERSION LATENCY.

POSITIVE FULL SCALE ERROR is the difference between the actual last code transition and its ideal value of

1½ LSB below positive full scale.

POWER SUPPLY REJECTION RATIO (PSRR) is a measure of how well the ADC rejects a change in the power

supply voltage. For the ADC12DL066, PSRR1 is the ratio of the change in Full-Scale Error that results from a

change in the d.c. power supply voltage, expressed in dB. PSRR2 is a measure of how well an a.c. signal riding

upon the power supply is rejected at the output.

SIGNAL TO NOISE RATIO (SNR) is the ratio, expressed in dB, of the rms value of the input signal to the rms

value of the sum of all other spectral components below one-half the sampling frequency, not including

harmonics or d.c.

SIGNAL TO NOISE PLUS DISTORTION (S/N+D or SINAD) Is the ratio, expressed in dB, of the rms value of the

input signal to the rms value of all of the other spectral components below half the clock frequency, including

harmonics but excluding d.c.

Copyright © 2004–2008, Texas Instruments Incorporated

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