Hi Freddy,
Louijie is correct. The AD9910 DRG and RAM use the same registers inside the part so only one can be functioning at a given time. However, the AD9910 has a second ramp generator exclusive for amplitude control, but it has some limitations. Read the Output Shift Keying section that starts on page 27 of the datasheet and the Automatic OSK mode described on page 28.
Message was edited by: Kevin.G - Incorrect