ADC121S021CIMF Datasheet, PDF (8/23 Pages) Texas Instruments – ADC121S021 Single Channel, 50 to 200 ksps, 12-Bit A/D Converter

ADC121S021
SNAS305H – JULY 2005 – REVISED MARCH 2013
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MISSING CODES are those output codes that will never appear at the ADC outputs. The ADC121S021 is
ensured 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 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 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:
A_f22 + + A_f62
THD = 20‡ log₁₀
A_f12
(1)
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.
THROUGHPUT TIME is the minimum time required between the start of two successive conversion. It is the
acquisition time plus the conversion time.
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