ADC12181 datasheet(10/17 Pages) NSC

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Specification Definitions

APERTURE JITTER is the variation in aperture delay from

sample to sample. Aperture jitter shows up as input noise.

APERTURE DELAY See Sampling Delay.

CLOCK DUTY CYCLE is the ratio of the time that the clock

waveform is high to the total time for one clock cycle.

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 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 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.

FULL SCALE ERROR is the difference between the input

voltage just causing a transition to positive full scale and

REF -1.5 LSB.

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

deviation of each individual code from a line drawn from

negative full scale (1⁄2 LSB below the first code transition)

through positive full scale (11⁄2 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. INL is commonly measured at

rated clock frequency with a ramp input.

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 dB.

PIPELINE DELAY (LATENCY) is the number of clock cycles

between initiation of conversion and the availability of that

conversion result at the output. New data is available at

every clock cycle, but the data lags the conversion by the

pipeline delay plus the Output Delay.

SAMPLING (APERTURE) DELAY is the time after the edge

of the clock to when the input signal is acquired or held for

conversion.

SIGNAL TO NOISE PLUS DISTORTION (S/(N+D) or SI-

NAD) 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 har-

monics but excluding dc.

SIGNAL TO NOISE RATIO (SNR) is the ratio of the rms

value of the input signal to the rms value of the other spectral

components below one-half the sampling frequency, not in-

cluding harmonics or dc.

SPURIOUS FREE DYNAMIC RANGE (SFDR) is the differ-

ence, expressed in dB, between the rms values of the input

signal and the peak spurious signal, where a spurious signal

is any signal present in the output spectrum that is not

present at the input.

TOTAL HARMONIC DISTORTION (THD) is the ratio of the

rms total of the first six harmonic components, to the rms

value of the input signal.

ZERO SCALE OFFSET ERROR is the difference between

the ideal input voltage (1⁄2 LSB) and the actual input voltage

that causes a transition from an output code of zero to an

output code of one.

ZERO ERROR See Zero Scale Offset Error.

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