REV. 0

AD13280

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DEFINITION OF SPECIFICATIONS

Analog Bandwidth

The analog input frequency at which the spectral power of the

fundamental frequency (as determined by the FFT analysis) is

reduced by 3 dB.

Aperture Delay

The delay between a differential crossing of ENCODE and

ENCODE command and the instant at which the analog input

is sampled.

Aperture Uncertainty (Jitter)

The sample-to-sample variation in aperture delay.

Differential Analog Input Resistance, Differential Analog

Input Capacitance, and Differential Analog Input Impedance

The real and complex impedances measured at each analog

input port. The resistance is measured statically and the capaci-

tance and differential input impedances are measured with a

network analyzer.

Differential Analog Input Voltage Range

The peak-to-peak differential voltage that must be applied to the

converter to generate a full-scale response. Peak differential

voltage is computed by observing the voltage from the other pin,

which is 180 degrees out of phase. Peak-to-peak differential is

computed by rotating the inputs phase 180 degrees and taking

the peak measurement again. The difference is then computed

between both peak measurements.

Differential Nonlinearity

The deviation of any code from an ideal 1 LSB step.

Encode Pulsewidth/Duty Cycle

Pulsewidth high is the minimum amount of time that the

ENCODE pulse should be left in Logic “1” state to achieve

rated performance; pulsewidth low is the minimum time

ENCODE pulse should be left in low state. At a given clock

rate, these specs define an acceptable Encode duty cycle.

Harmonic Distortion

The ratio of the rms signal amplitude to the rms value of the

worst harmonic component.

Integral Nonlinearity

The deviation of the transfer function from a reference line

measured in fractions of 1 LSB using a “best straight line”

determined by a least square curve fit.

Minimum Conversion Rate

The encode rate at which the SNR of the lowest analog signal

frequency drops by no more than 3 dB below the guaranteed limit.

Maximum Conversion Rate

The encode rate at which parametric testing is performed.

Output Propagation Delay

The delay between a differential crossing of ENCODE and

ENCODE command and the time when all output data bits are

within valid logic levels.

Overvoltage Recovery Time

The amount of time required for the converter to recover to

0.02% accuracy after an analog input signal of the specified

percentage of full scale is reduced to midscale.

Power Supply Rejection Ratio

The ratio of a change in input offset voltage to a change in

power supply voltage.

Signal-to-Noise-and-Distortion (SINAD)

The ratio of the rms signal amplitude (set at 1 dB below full

scale) to the rms value of the sum of all other spectral compo-

nents, including harmonics but excluding dc. May be reported

in dB (i.e., degrades as signal level is lowered) or in dBFS

(always related back to converter full scale).

Signal-to-Noise Ratio (without Harmonics)

The ratio of the rms signal amplitude (set at 1 dB below full

scale) to the rms value of the sum of all other spectral compo-

nents, excluding the first five harmonics and dc. May be reported

in dB (i.e., degrades as signal level is lowered) or in dBFS

(always related back to converter full scale).

Spurious-Free Dynamic Range

The ratio of the rms signal amplitude to the rms value of the

peak spurious spectral component. The peak spurious compo-

nent may or may not be a harmonic.

Transient Response

The time required for the converter to achieve 0.02% accuracy

when a one-half full-scale step function is applied to the ana-

log input.

Two-Tone Intermodulation Distortion Rejection

The ratio of the rms value of either input tone to the rms value

of the worst third order intermodulation product; reported in dBc.

ENC,

ENC

D[11:0]

DRY

N

N+1

N+2

N+3

N+4

N

N+1

N+2

N+3

N+4

N–3N–2N–1N

Figure 1. Timing Diagram