I wanted to simulate, Evaluation board schematic as per provided in the AD9856 datasheet.
I am using ADIsimPE but in that, I am not getting AD9856 part details to place it. Also, I was unable to get AD8320 for the same.
I made a hardware interface of FPGA and AD9856 through SPI. It works as per mentioned in the datasheet for single tone frequency.
But in continuous mode when known data of 12 bit is provided to DDC, I am not getting properly modulated waveform at the IF connector.
I am using Ref Clock multiplier to make sampling frequency of 200 MHz from the oscillator of 50 MHz.
Data_I send on a frequency of 9.8208 MHz by making TxEnable high for the same and Data_Q sent at same frequency using Tx_Enable signal LOW.
If anyone has screenshots of results of QPSK modulated data then please share.
Unfortunately, the AD9856 is not available on ADIsimPE. As for the AD8320, this part is already obsolete.
As for the continuous mode, the data sheet indicates that "Do not engage continuous mode simultaneously with the REFCLK multiplier function. This corrupts the CIC interpolating filter, forcing unrecoverable mathematical overflow that can only be resolved by issuing a RESET command. The problem is due to the PLL failing to be locked to the reference clock while nonzero data is being clocked into the interpolation stages from the data inputs. The recommended sequence is to first engage the REFCLK multiplier function (allowing at least 1 ms for loop stabilization) and then engage continuous mode via software."