2

f1

2

f10

2

f2

10

‡

A

A

+

+

A

log

THD = 20

ADC128S102

www.ti.com

SNAS298D – AUGUST 2005 – REVISED JANUARY 2011

MISSING CODES are those output codes that will never appear at the ADC outputs. These codes cannot be

reached with any input value. The ADC128S102 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 d.c. or

the harmonics included in THD.

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.

SPURIOUS FREE DYNAMIC RANGE (SFDR) is the difference, expressed in dB, between the desired signal

amplitude to the amplitude of the peak spurious spectral component, where a spurious spectral component is

any signal present in the output spectrum that is not present at the input and may or may not be a harmonic.

TOTAL HARMONIC DISTORTION (THD) is the ratio, expressed 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

(2)

first 9 harmonic frequencies.

THROUGHPUT TIME is the minimum time required between the start of two successive conversions. It is the

acquisition time plus the conversion and read out times. In the case of the ADC128S102, this is 16 SCLK

periods.

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