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ADS5474

SLAS525C – JULY 2007 – REVISED JANUARY 2016

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11 Device and Documentation Support

11.1 Device Support

11.1.1 Device Nomenclature

Analog Bandwidth The analog input frequency at which the power of the fundamental is reduced by 3 dB with

respect to the low-frequency value.

Aperture Delay The delay in time between the rising edge of the input sampling clock and the actual time at

which the sampling occurs.

Aperture Uncertainty (Jitter) The sample-to-sample variation in aperture delay.

Clock Pulse Duration/Duty Cycle The duty cycle of a clock signal is the ratio of the time the clock signal

remains at a logic high (clock pulse duration) to the period of the clock signal, expressed as a

percentage.

Differential Nonlinearity (DNL) An ideal ADC exhibits code transitions at analog input values spaced exactly 1

LSB apart. DNL is the deviation of any single step from this ideal value, measured in units of LSB.

Common-Mode Rejection Ratio (CMRR) CMRR measures the ability to reject signals that are presented to

both analog inputs simultaneously. The injected common-mode frequency level is translated into

dBFS, the spur in the output FFT is measured in dBFS, and the difference is the CMRR in dB.

Effective Number of Bits (ENOB) ENOB is a measure in units of bits of converter performance as compared to

the theoretical limit based on quantization noise:

ENOB = (SINAD – 1.76)/6.02

(7)

Gain Error

Gain error is the deviation of the ADC actual input full-scale range from its ideal value, given as a

percentage of the ideal input full-scale range.

Integral Nonlinearity (INL) INL is the deviation of the ADC transfer function from a best-fit line determined by a

least-squares curve fit of that transfer function. The INL at each analog input value is the difference

between the actual transfer function and this best-fit line, measured in units of LSB.

Offset Error Offset error is the deviation of output code from mid-code when both inputs are tied to common-

mode.

Power-Supply Rejection Ratio (PSRR) PSRR is a measure of the ability to reject frequencies present on the

power supply. The injected frequency level is translated into dBFS, the spur in the output FFT is

measured in dBFS, and the difference is the PSRR in dB. The measurement calibrates out the

benefit of the board supply decoupling capacitors.

(dB to carrier) when the absolute power of the fundamental is used as the reference, or dBFS (dB

to full-scale) when the power of the fundamental is extrapolated to the converter full-scale range.

(8)

SINAD is either given in units of dBc (dB to carrier) when the absolute power of the fundamental is

used as the reference, or dBFS (dB to full-scale) when the power of the fundamental is

extrapolated to the converter full-scale range.

(9)

Temperature Drift Temperature drift (with respect to gain error and offset error) specifies the change from the

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