Datasheet

2
1f
2
6f
2
2f
10
‡
A
A++A
log20=THD

ADC102S021
SNAS281G –FEBRUARY 2005–REVISED MARCH 2013 www.ti.com
code value.
INTERMODULATION DISTORTION (IMD) is the creation of additional spectral components that are present at
the output and are not present at the input and result from two sinusoidal frequencies being applied to the
ADC input at the same time. It is defined as the ratio of the power in the second and third order
intermodulation products to the sum of the power in both of the original frequencies. IMD is usually
expressed in dB.
MISSING CODES are those output codes that will never appear at the ADC outputs. These codes cannot be
reached with any input value. The ADC102S021 is specified 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 at the
converter output to the rms value of the sum of all other spectral components below one-half the sampling
frequency, not including d.c. or harmonics included in the THD specification.
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 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, excluding d.c.
TOTAL HARMONIC DISTORTION (THD) is the ratio, expressed in dB or 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)
where Af
1
is the RMS power of the input frequency at the output and Af
2
through Af
6
are the
RMS power in the first 5 harmonic frequencies. Accurate THD measurement requires a
spectrally pure sine wave (monotone) at the ADC input.
THROUGHPUT TIME is the minimum time required between the start of two successive conversion. It is the
acquisition time plus the conversion and read out times. In the case of the ADC102S021, this is 16 SCLK
periods.
8 Submit Documentation Feedback Copyright © 2005–2013, Texas Instruments Incorporated
Product Folder Links: ADC102S021