Hello,
I'm using the AD9910/PCBZ evaluation board (UG-207) and trying to generate a 30 MHz single-tone output from a 100 MHz external reference clock, measured on an oscilloscope. I'd appreciate help troubleshooting, as I only see noise on the scope instead of a clean sine wave.
Setup:
• Signal generator (Keysight E5071C) set to output a 100 MHz CW signal, confirmed correct with 100 MHz visible on the oscilloscope directly.
• Signal generator output connected to the board's REF CLOCK INPUT (external clock, not the onboard 25 MHz crystal).
• DAC output taken from the "Unfiltered IOUT" SMA connector, connected to the oscilloscope.
• Board powered via TB1/TB2 per Table 2 in UG-207 (VCC_USB 3.3V, DVDD_IO 3.3V, DVDD 1.8V, DAC_VDD 3.3V, CLK_VDD 1.8V). Corresponding power LED is lit.
• Jumpers set for PC/USB control mode per Table 3 (W1, W2, W4 enabled; W5, W6, W3 jumpered).
• USB connected; USB status LED blinking as expected.
• Evaluation software shows all-green status, and indicates the board is connected to the AD9910.
Software configuration:
• Control window: External Clock field set to 100.00000 MHz.
• Enable Multiplier: left unchecked/disabled (bypassing the PLL multiplier, since the loop filter components are not populated on this board).
• Profiles window, Profile 0: Output Freq set to 30.000000 MHz via the Edit Output Frequency dialog.
• Enable Profile ASF: left unchecked (so amplitude runs at full scale).
• Profile 0 selected as Active.
• Clicked LOAD; the LOAD indicator shows the I/O update was sent (no longer blinking/pending).
Problem:
Despite all of the above, the oscilloscope only shows noise on the DAC output — no visible 30 MHz sine wave.
Any guidance on what else to check would be greatly appreciated.
Thank you!
