My project need to work at 40KHz. I am trying to use a simple test circuit to get a 40KHz sinusoidal wave first. I connect a source to the output directly. I set the sample rate to 96KHz. However, the highest frequency i can get is around 20KHz. After I set the sample rate to 192KHz, the highest frequency is about 22KHz. The PLL_MODE0 is 0 and PLL_MODE1 is 1.
The figure 8, 9, and 10 in the datasheet show there is a filter to stop the signal at 22KHz. But I believe it should work for 40KHz signal under the 96KHz and 192KHz sample rate.
Could you please tell me how to get high frequency using ADAU1401A?