Antialiasing Filter with an Improved S/N Ratio

If a CCD low-pass filter is used for antialiasing, a higher data rate is necessary at the input compared to the output. This difference in the data rate is used to increase the signal-to-noise ratio. By adding a given number of consecutive charge packets at the output stage, the output data rate can be reduced until the Nyquist theorem for the output signal is violated. By summing up those charge packets, the signal is added arithmetically whereas the noise, not being correlated, is added geometrically. This results in an improvement of the S/N ratio equal to the number of charge packets added.