AD9208 has a small signal at FS/4 and the small signal amplitude will change when resetting the JESD bus. ADC cannot be powered off. The ADC configuration is dual -channel DDC mode, L = 8, F = 1, M = 2. ADC sampling rate 3Gbps, FFT points 1047586, DDC is FS/4Hz IF mode. Sometimes the amplitude is large, exceeding 20dB of noise and sometimes the amplitude is small, only exceeding the noise 5 ~ 10dB. If the JESD bus of the ADC is not reset, the small signal amplitude will not change. The specific configuration of the ADC is:
After the ADC is powered on, all the content is configured for the first time. The second configuration only configures 0x0571 to write 0x15, 0x0571 to write 0x14. A small signal amplitude will change a lot. If Jesd is not reset, the small signal does not change. Help analyze what the reason is, thank you.