AD9106 and white Noise

Question

Hi and good morning together, 
 we evaluate the AD9106. We have the AD9106-EBZ eval board. 
 Beside of sine waveform generation, we have to generate noise. We are using the windows demo software 
 If I configure to DDS, 100kHz, i get a perfect sine with an amplitude of 1Vss. After i switch to random to get white noise (PRESTORE_SEL1 to 2) i get noise, but only with an amplitude of about 40mVss. How can i get noise with an higher amplitude? 
 
 Other question: 
 Is the AD9106 the best choice or would you sugest an other DDS chip for the following customer requirements: 
 Sine Wave Generation: - Range 15kHz to 65kHz - Freq resolution: <=1Hz (I think we can archive this with an 16.777216Mhz clock - Very low THD: at least <0,1 % - Very good SNR: at least 60 dB - 2. Second sine wave with the same parameter but with 90&deg; phase shift. Noise Generation: - white noise from 15kHz to 65kHz 
 Regards 
 Falko

ADIApproved · Accepted Answer

Hello, 
 Yes, you can generate the sine waves as you said. You use two channels, set one's phase offset to be 0x0, the other 0x4000 (pi). 
 The pseudo random sequence is only single bit, and you can't band limit it, so I am not sure it will meet your need. You can double the magnitude by increasing the digital gain from 1 to almost 2 (0x400 to 0x7FF). Alternatively you could generate you own noise and store them in the RAM. Then you can have multi-level and band-limited noise, but be limited to 4k samples. 
 Regards, 
 Will)

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AD9106 and white Noise