The first code transition should occur at an analog value one-half LSB above negative full scale. The lasttransition should occur at an analog value one and one-half LSB below the nominal full scale. Gain error isthe deviation of the actual difference between first and last code transitions and the ideal differencebetween first and last code transitions.Signal-to-Noise Ratio + Distortion (SINAD)SINAD is the ratio of the rms value of the measured input signal to the rms sum of all other spectralcomponents below the Nyquist frequency, including harmonics but excluding dc. The value for SINAD isexpressed in decibels.Effective Number of Bits (ENOB)For a sine wave, SINAD can be expressed in terms of the number of bits. Using the followingformula,it is possible to get a measure of performance expressed as N, the effectivenumber of bits. Thus, effective number of bits for a device for sine wave inputs at a given input frequencycan be calculated directly from its measured SINAD.Total Harmonic Distortion (THD)THD is the ratio of the rms sum of the first nine harmonic components to the rms value of the measuredinput signal and is expressed as a percentage or in decibels.Spurious Free Dynamic Range (SFDR)SFDR is the difference in dB between the rms amplitude of the input signal and the peak spurious signa |
|
|