Editing Analog-to-digital converter (section)

===Sliding scale principle===
The sliding scale or randomizing method can be employed to greatly improve the linearity of any type of ADC, but especially flash and successive approximation types.  For any ADC the mapping from input voltage to digital output value is not exactly a [[floor function|floor]] or [[ceiling function]] as it should be. Under normal conditions, a pulse of a particular amplitude is always converted to the same digital value. The problem lies in that the ranges of analog values for the digitized values are not all of the same widths, and the [[differential linearity]] decreases proportionally with the divergence from the average width. The sliding scale principle uses an averaging effect to overcome this phenomenon. A random, but known analog voltage is added to the sampled input voltage. It is then converted to digital form, and the equivalent digital amount is subtracted, thus restoring it to its original value. The advantage is that the conversion has taken place at a random point. The statistical distribution of the final levels is decided by a weighted average over a region of the range of the ADC. This in turn desensitizes it to the width of any specific level.<ref>{{Harvtxt|Knoll|1989|pp=665–666}}</ref><ref>{{Harvtxt|Nicholson|1974|pp=315–316}}</ref>