ADC08D1000EVAL datasheet(14/31 Pages) NSC

14 / 31 page

Specification Definitions (Continued)

SIGNAL TO NOISE RATIO (SNR) is the ratio, expressed in

dB, of the rms value of the input signal at the output 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 SI-

NAD) is the ratio, expressed in dB, of the rms value of the

input signal at the output to the rms value of all of the other

spectral components below half the input clock frequency,

including harmonics but excluding d.c.

SPURIOUS-FREE DYNAMIC RANGE (SFDR) is the differ-

ence, expressed in dB, between the rms values of the input

signal at the output 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 ex-

pressed in dB, of the rms total of the first nine harmonic

levels at the output to the level of the fundamental at the

output. THD is calculated as

where A

f1 is the RMS power of the fundamental (output)

frequency and A

f2 through Af10 are the RMS power of the

first 9 harmonic frequencies in the output spectrum.

– Second Harmonic Distortion (2nd Harm) is the differ-

ence, expressed in dB, between the RMS power in the input

frequency seen at the output and the power in its 2nd

harmonic level at the output.

– Third Harmonic Distortion (3rd Harm) is the difference

expressed in dB between the RMS power in the input fre-

quency seen at the output and the power in its 3rd harmonic

level at the output.

Transfer Characteristic

20097422

FIGURE 2. Input / Output Transfer Characteristic

ADC08D1000EVAL Datasheet(PDF) 14 Page - National Semiconductor (TI)