Specification Definitions

ACQUISITION TIME is the time required for the ADC to

acquire the input voltage. During this time, the hold capacitor

is charged by the input voltage.

APERTURE DELAY is the time between the fourth falling

edge of SCLK and the time when the input signal is internally

acquired or held for conversion.

CONVERSION TIME is the time required, after the input

voltage is acquired, for the ADC to convert the input voltage

to a digital word.

CHANNEL-TO-CHANNEL ISOLATION is resistance to cou-

pling of energy from one channel into another channel.

CROSSTALK is the coupling of energy from one channel

into another channel. This is similar to Channel-to-Channel

Isolation, except for the sign of the data.

DIFFERENTIAL NON-LINEARITY (DNL) is the measure of

the maximum deviation from the ideal step size of 1 LSB.

DUTY CYCLE is the ratio of the time that a repetitive digital

waveform is high to the total time of one period. The speci-

fication here refers to the SCLK.

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 is the deviation of the last code transition

(111...110) to (111...111) from the ideal (V

after adjusting for offset error.

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

deviation of each individual code from a line drawn from

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 an individual ADC input at the

same time. It is defined as the ratio of the power in either the

second or the third order intermodulation products to the

sum of the power in both of the original frequencies. Second

order products are f

wave input frequencies. Third order products are (2f

and (f

MISSING CODES are those output codes that will never

appear at the ADC outputs. The ADC088S102 is guaranteed

not to have any missing codes.

OFFSET ERROR is the deviation of the first code transition

(000...000) to (000...001) from the ideal (i.e. GND + 0.5

LSB).

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 compo-

nents below half the clock frequency, including harmonics

but excluding d.c.

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, including harmonics but excluding d.c.

TOTAL HARMONIC DISTORTION (THD) is the ratio, ex-

pressed in dBc, of the rms total of the first five harmonic

components at the output to the rms level of the input signal

frequency as seen at the output. THD is calculated as

where A

output and A

harmonic frequencies.

THROUGHPUT TIME is the minimum time required between

the start of two successive conversions. It is the acquisition

time plus the conversion time.

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