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6308A–DRMSD–10-May-07

ATSAM2195

8.

Dither Modes Description (Dithering Signal Programmability)

Dithering is used to attenuate the so-called idle tones caused by correlation between DAC input

signal and truncation noise. This correlation manifests as spurious signals in the audio band and

hence can be perceived by the user. The addition of a random digital signal to the truncator input

in the digital modulator has been proven to be very effective to reduce the presence of idle

tones. However, this is actually a noisy signal so that its power must be traded-off with the

required dynamic range. For better control, the ATSAM2195 allows programmability of the dith-

ering signal power as shown below.

dith[1:0]

Mode description

Comments

00

No dither

01

Dither signal power = -30dBFS

Minimum recommended dither.

10

Dither signal power = -27dBFS

Typical value

11

Dither signal power = -24dBFS

Maximum recommended value. Above it dither noise may

become dominant.