I am planning to use single AD9914. Do I need DAC calibration ?
There seems no difference in the RF output between calibrated output and non-calibrated output?
You should always initiate a DAC CAL after power up. The DAC CAL optimizes the internal timing between the internal system clock and the internal 12 input DAC codes. Per the diagram attached, the LSB Eye pattern is depicted. Essentially, the eye pattern is adjusted in time (via DAC CAL routine) such that the system clock samples the DAC codes in the middle (where the LSB is settled). This gives the most robust timing. If the timing was marginal (sampled closer to the LSB transitions), the DAC output noise floor could rise/degrade. So, if you don't do a DAC CAL and the performance appears fine note that ambient temperature changes could impact timing and degrade performance.
Thanks for the answer
The actual problem is not making a calibration or not. We are calibrating at the startup. There is no problem with the making or not making. But is the calibration is valid all the time?. İs there any indication for the BAD CALIBRATION( like "PLL LOCK Signals" in the PLLs) so that we can think that the calibration is not valid and re-calibrate it.
Will there be any change in the output if we re-calibrate the previously calibrated DDC IC?
If a DAC calibration has been omitted, the main indication is degradation in both phase noise or noise floor. That said, once a DAC calibration is performed, the device should perform over temperature and should not require an additional calibration. However, if power is lost or a power down is performed, another DAC calibration is required.
I am from HAVELSAN EHSİM (Ank) and at one of our projects we suppose to drive and use AD9914 (with Xilinx fpga.)
If you can share your infos or keep in contact with me from my below infos, i guess it would be a nice plus for both of us.Hope to hear from you.
Sercan EgilmezkolExp. HW Eng.---e-mail adr. is deleted by Sercan---
By the way: I know the answer. As the other friend says DAC Cal is a must.
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