Definitions of specified parameters

RHF1201

14/18

8

Definitions of specified parameters

Static parameters

Static measurements are performed using the histograms method on a 2 MHz input signal,

sampled at 50 Msps, which is high enough to fully characterize the test frequency response.

The input level is +1 dBFS to saturate the signal.

Differential non linearity (DNL)

The average deviation of any output code width from the ideal code width of 1 LSB.

Integral non linearity (INL)

An ideal converter exhibits a transfer function which is a straight line from the starting code

to the ending code. The INL is the deviation from this ideal line for each transition.

Dynamic parameters

Dynamic measurements are performed by spectral analysis, applied to an input sine wave

of various frequencies and sampled at 50 Msps.

Spurious free dynamic range (SFDR)

The ratio between the power of the worst spurious signal (not always an harmonic) and the

amplitude of fundamental tone (signal power) over the full Nyquist band. It is expressed in

dBc.

Total harmonic distortion (THD)

The ratio of the rms sum of the first five harmonic distortion components to the rms value of

the fundamental line. It is expressed in dB.

Signal to noise ratio (SNR)

The ratio of the rms value of the fundamental component to the rms sum of all other spectral

harmonics. SNR is reported in dB.

Signal to noise and distortion ratio (SINAD)

Similar ratio as for SNR but including the harmonic distortion components in the noise figure

(not DC signal). It is expressed in dB.

The effective number of bits (ENOB) is easily deduced from the SINAD, using the formula:

SINAD = 6.02

× ENOB + 1.76 dB.

expression becomes:

SINAD = 6.02

The ENOB is expressed in bits.