THS1230CPWR datasheet(18/22 Pages) TI

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Analog Input Bandwidth

Output Timing

Signal-to-Noise Ratio + Distortion (SINAD)

Effective Number of Bits (ENOB)

Total Harmonic Distortion (THD)

Spurious Free Dynamic Range (SFDR)

THS1230

SLAS291B – OCTOBER 2000 – REVISED MARCH 2004

The analog input bandwidth is defined as the maximum frequency of a 1-dBFS input sine wave that can be

applied to the device for which an extra 3-dB attenuation is observed in the reconstructed output signal.

Output timing td(O) is measured from the 50% level of the CLK input falling edge to the 10%/90% level of the

digital output. The digital output load is not higher than 10 pF.

Output hold time th(O) is measured from the 50% level of the CLK input falling edge to the10%/90% level of the

digital output. The digital output load is not less than 2 pF.

Aperture delay td(A) is measured from the 50% level of the CLK input to the actual sampling instant.

The OE signal is asynchronous.

OE timing td(PZ) is measured from the VIH(min) level of OE to the high-impedance state of the output data. The

digital output load is not higher than 10 pF.

OE timing td(EN) is measured from the VIL(max) level of OE to the instant when the output data reaches VOH(min) or

VOL(max) output levels. The digital output load is not higher than 10 pF.

SINAD is the ratio of the rms value of the measured input signal to the rms sum of all other spectral components

below the Nyquist frequency, including harmonics but excluding dc. The value for SINAD is expressed in

decibels.

For a sine wave, SINAD can be expressed in terms of the number of bits. Using the following formula,

•

N = (SINAD – 1.76)/6.02

it is possible to get a measure of performance expressed as N, the effective number of bits. Thus, effective

number of bits for a device for sine wave inputs at a given input frequency can be calculated directly from its

measured SINAD.

THD is the ratio of the rms sum of the first six harmonic components to the rms value of the measured input

signal and is expressed as a percentage or in decibels.

SFDR is the difference in dB between the rms amplitude of the input signal and the peak spurious signal.

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