Datasheet

2
f1
2
f10
2
f2
10
‡
A
A++A
logTHD = 20

ADC128S052
SNAS333D –AUGUST 2005–REVISED MARCH 2013 www.ti.com
GAIN ERRORis the deviation of the last code transition (111...110) to (111...111) from the ideal (V
REF
- 1.5 LSB),
after adjusting for offset error.
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 an individual ADC input at the same time. It is defined as the ratio
of the power in both the second or the third order intermodulation products to the power in one of the
original frequencies. Second order products are f
a
± f
b
, where f
a
and f
b
are the two sine wave input
frequencies. Third order products are (2f
a
± f
b
) and (f
a
± 2f
b
). IMD is usually expressed in dB.
MISSING CODESare those output codes that will never appear at the ADC outputs. These codes cannot be
reached with any input value. The ADC128S052 is guaranteed not to have any missing codes.
OFFSET ERRORis 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
• where A
f1
is the RMS power of the input frequency at the output and A
f2
through A
f6
are the RMS
power in the first 5 harmonic frequencies. (2)
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 ADC128S052, this is 16 SCLK
periods.
8 Submit Documentation Feedback Copyright © 2005–2013, Texas Instruments Incorporated
Product Folder Links: ADC128S052