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AD9963 with TXCLK as an input?

Category: Hardware
Product Number: AD9963

I'm using the AD9963 in FULL DUPLEX mode and I'd like to externally drive the TXCLK so that I can transmit with DDR (or at least using interpolators).

If I configure the AD9963 to output the clock with (TX_SDR | TXCLK_MD=10), all works fine. I get the doubled reference clock back and can send samples which appear on the DAC without issue.

However, if I configure it to input the clock (TXCLK_MD=01), either in TX_SDR or not, no samples appear output by the DAC. The scope output looks identical (aside from the duty cycle of the clock doubler) regardless of whether the FPGA is driving the clock or the AFE is. However, one has output, the other does not.

The only differences between these two scenarios:

"No Output" Case "With Output" Case
TXCLK_MD 2'b01 2'b10
Clock Driven by FPGA Yes No

Am I missing some other required setting?

I tried using the AD9963_SPI program, but it requires a really ancient version of LabView runtime I can no longer download.

No Output: 

With Output: 

Thanks in advance!