Keysight Technologies 3458A Guide D'utilisation page 496

E High Resolution Digitizing With the 3458A
levels. Integral non-linearity is the maximum deviation of the linearity curve from a
leastmean-square fit. In general, differential non-linearity may cause significant
measurement error if a low level signal happens to fall on that part of the ADC
transfer function with the differential non-linearity error. Integral non-linearity in
an ADC is generally more detrimental when digitizing full scale signals.
Realize that the transfer function for an ADC is very dependent upon the slew rate
(dV/dt). The transfer function for a static DC input level may appear close to the
ideal. The transfer function under dynamic operating conditions may exhibit
numerous errors as shown in
An inescapable reality in any measurement is the attendant noise with increasing
bandwidth. The effects of random measurement noise can be reduced by
averaging the measurements. Caused by Johnson noise and other circuit related
noise as well as noise on the input signal, the removal of this noise always costs
measurement time. A measure of the quality of a digitizing instrument, called the
"effective bits" of resolution, combines noise with ADC linearity to show the usable
resolution of the digitizer:
effective bits = N -log
496
Figure E-12.
(rms error (actual)/rms error (ideal))
2
Keysight 3458A User's Guide