11

Dynamic Performance Definitions

Fast Fourier Transform (FFT) techniques are used to

evaluate the dynamic performance of the HI5805. A low

distortion sine wave is applied to the input, it is coherently

sampled, and the output is stored in RAM. The data is then

transformed into the frequency domain with an FFT and

analyzed to evaluate the dynamic performance of the A/D.

The sine wave input to the part is -0.5dB down from full scale

for all these tests. SNR and SINAD are quoted in dB. The

distortion numbers are quoted in dBc (decibels with respect

to carrier) and DO NOT include any correction factors for

normalizing to full scale.

Signal-to-Noise Ratio (SNR)

SNR is the measured RMS signal to RMS noise at a

specified input and sampling frequency. The noise is the

RMS sum of all of the spectral components except the

fundamental and the first five harmonics.

Signal-to-Noise + Distortion Ratio (SINAD)

SINAD is the measured RMS signal to RMS sum of all

other spectral components below the Nyquist frequency,

Effective Number Of Bits (ENOB)

The effective number of bits (ENOB) is calculated from the

SINAD data by:

fullscale.

Total Harmonic Distortion (THD)

THD is the ratio of the RMS sum of the first 5 harmonic

components to the RMS value of the fundamental input

signal.

2nd and 3rd Harmonic Distortion

This is the ratio of the RMS value of the applicable

harmonic component to the RMS value of the fundamental

input signal.

Spurious Free Dynamic Range (SFDR)

SFDR is the ratio of the fundamental RMS amplitude to the

RMS amplitude of the next largest spur or spectral

Intermodulation Distortion (IMD)

Nonlinearities in the signal path will tend to generate

present at the inputs. The ratio of the measured signal to

the distortion terms is calculated. The terms included in the

tone 6dB below full scale.

ENOB = SINAD + V

()/6.02,

HI5805