PRELIMINARY TECHNICAL DATA

AD9910

Rev. PrD| Page 13 of 13

PR06464-0-10/06(PrD)

quency parameter, thereby increasing its affect on the DDS fre-

quency by a factor of 2. The FM Gain word effectively controls

the maximum frequency range spanned by the data word.

Table 2: Parallel port destination bits

Destination

Bits <1:0>

Data Word Parti-

tioning <17:2>

DDS Signal Control

Parameter

Remarks

00

<17:4>

14-bit amplitude parame-

ter (unsigned integer)

<3:0> are ignored.

01

<17:2>

16-bit phase parameter

(unsigned integer)

10

<17:2>

32-bit frequency parame-

ter (unsigned integer)

The alignment of 16-bit data word with the 32-bit frequency pa-

rameter is controlled by a 4-bit FM Gain word in the programming

registers.

11

<17:10>

<9:2>

8 bits amplitude (un-

signed integer)

8 bits phase (unsigned

integer)

The MSB of the data word amplitude aligns with the MSB of the

DDS's 14-bit amplitude parameter. The 6 LSBs of the DDS's ampli-

tude parameter are assigned from bits <5:0> of the ASF register.

The MSB of the data word phase aligns with the MSB of the DDS's

16-bit phase parameter. The 8 LSBs of the DDS's phase parameter

are assigned from bits <7:0> of the POW register. The resulting 16-

Figure 7: Parallel data port modulation mode