New methods for determining the number of effective bits of A/D converters based on eigendecomposition
For calculating the number of effective bits, we measure the rms
noise by fitting the ADC's output signal to a curve. Thus, a nonlinear
equation system is obtained and several Newton type iterative algorithms
are used to resolve it. We established that a good estimation of the
frequency for the first computation of an iterative process is
necessary. To remove this problem, we proposed new methods based on the
eigendecomposition of the autocorrelation matrix in the input signal.
The first, using the MUSIC method gives an accurate prime estimation of
the frequency for the model which fits the output data. Then, this value
is introduced in a Newton type algorithm for a good estimation of the
noise. The second, more attractive, provides a direct accurate
estimation of the noise. Condition testing and simulations will be given
to validate these new methods