Datasheet

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A++A

log20=THD

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ADC081S021

SNAS308E –APRIL 2005–REVISED MARCH 2013

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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 the ADC081S021 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 ADC081S021 outputs. The ADC081S021

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 +

1 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 where A

is the RMS power of the input

frequency at the output and A

through A

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.

TOTAL UNADJUSTED ERROR is the worst deviation found from the ideal transfer function. As such, it is a

comprehensive specification which includes full scale error, linearity error, and offset error.

Product Folder Links: ADC081S021