I am prototyping a design using AD9835 dds chip. I have no previous experience of using this part. Serial programming interface with PIC controller is working fine using various sequences of instructions and desired frequency is output. The output signal seems very low level to me, about 47mV pk-pk. I use internal voltage reference and REFOUT connects to REFIN; but I measure 0V here. Also I notice a considerable delay on power up of 30 seconds or more before any output appears. I tried a second chip with the same results. Are my observations typical for this part ?