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3/10/97

SPT7921

SPECIFICATION DEFINITIONS

APERTURE DELAY

Aperture delay represents the point in time, relative to the

rising edge of the CLOCK input, that the analog input is

sampled.

APERTURE JITTER

The variations in aperture delay for successive samples.

DIFFERENTIAL GAIN (DG)

A signal consisting of a sine wave superimposed on various

DC levels is applied to the input. Differential gain is the

maximum variation in the sampled sine wave amplitudes at

these DC levels.

DIFFERENTIAL PHASE (DP)

A signal consisting of a sine wave superimposed on various

DC levels that is applied to the input. Differential phase is the

maximum variation in the sampled sine wave phases at these

DC levels.

EFFECTIVE NUMBER OF BITS (ENOB)

SINAD = 6.02N + 1.76, where N is equal to the effective

number of bits.

N =

SINAD - 1.76

6.02

+/- FULL-SCALE ERROR (GAIN ERROR)

Difference between measured full scale response

[(+Fs) - (-Fs)] and the theoretical response (+4 V -2 LSBs)

where the +FS (full scale) input voltage is defined as the

output transition between 1-10 and 1-11 and the -FS input

voltage is defined as the output transition between 0-00 and

0-01.

INPUT BANDWIDTH

Small signal (50 mV) bandwidth (3 dB) of analog input stage.

DIFFERENTIAL NONLINEARITY (DNL)

Error in the width of each code from its theoretical value.

INTEGRAL NONLINEARITY (INL)

Linearity error refers to the deviation of each individual code

(normalized) from a straight line drawn from -Fs through +Fs.

The deviation is measured from the edge of each particular

code to the true straight line.

OUTPUT DELAY

Time between the clock's triggering edge and output data

valid.

OVERVOLTAGE RECOVERY TIME

The time required for the ADC to recover to full accuracy after

an analog input signal 125% of full scale is reduced to 50%

of the full-scale value.

SIGNAL-TO-NOISE RATIO (SNR)

The ratio of the fundamental sinusoid power to the total noise

power. Harmonics are excluded.

SIGNAL-TO-NOISE AND DISTORTION (SINAD)

The ratio of the fundamental sinusoid power to the total noise

and distortion power.

TOTAL HARMONIC DISTORTION (THD)

The ratio of the total power of the first 64 harmonics to the

power of the measured sinusoidal signal.

SPURIOUS FREE DYNAMIC RANGE (SFDR)

The ratio of the fundamental sinusoidal amplitude to the

single largest harmonic or spurious signal.