Category: Hardware
Product Number: AD9106
Hello. This is in regards to a post we made here on the engineer zone.
1.We noticed some heating issues lately on the EVAL-AD9106. We have the operational amplifiers enabled and are powering it with a RIGOL variable power supply sending 7V @ 0.17A into port P15. The board is additionally mounted onto an Arduino UNO R3 as a shield. The attached images show our setup.We source from the DDS and clock with the on board crystal oscillator of 156.25Mhz to produce sine waves on each of the outputs. At frequencies in the kHz range (0-100kHz), when we alter the dgain values, we see that the amplitude of the specified channel climbs by about 1mV rms shortly after being set. For example, on channel 4, with a dgain of 4000, we see an amplitude of 470.1mv rms that climbs to 471.1,V rms within 30s or so. Applying cold air to the board lowers the amplitude so we believe the issues are heat related. We didn't see this behaviour before on either of the 2 EVAL-AD9106 cards we have. We are operating at room temperature, but it's possible that the room has gone up a degree or 2 since we last used the cards.
Are there any recommendations to resolve this issue?
2.Beyond that, we are looking for advice on the best way to set amplitudes on the AD9106. We want to operate in the 0-100kHz range. How can we convert user specified amplitudes (like 300mV) to proper dgain values?
3.We notice that the amplitudes do shift a little with the DDS frequency. For example, at 100kHz, channel 4 at dgain 4000 has 470.1mV, but when we switch to 100Hz, it drops to 468mV rms. How can we account for, or eliminate, this shift?
Thanks
