User`s guide

196 Agilent X-Series Signal Generators User’s Guide
Basic Digital Operation (Option 653/655/656/657)
Scaling a Waveform
How Scaling Eliminates DAC Over–Range Errors
Scaling reduces the amplitude of the baseband
waveform while maintaining its basic shape and
characteristics, such as peak–to–average power
ratio. If the fast–rising baseband waveform is
scaled enough to allow an adequate margin for
the interpolator filter overshoot, the interpolator
filter can calculate sample points that include
the ripple effect and eliminate the over–range
error (see the figure at the right).
Although scaling maintains the basic shape of
the waveform, excessive scaling can compromise
waveform integrity. For example, if the bit
resolution becomes too low the waveform
becomes corrupted with quantization noise. To
achieve maximum accuracy and optimize
dynamic range, scale the waveform no more
than is required to remove the DAC over–range
error. Optimum scaling varies with waveform
content.