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ADF4159 can't lock the VCO using EV-ADF4159EB3Z

Question asked by Jing@ustc on May 27, 2018
Latest reply on May 30, 2018 by Jing@ustc

I’m using the evaluation board EV-ADF4159EB3Z to understand how the ADF4159 component works and how to program it. I use my own VCO and the loop filter on the evaluation board EV-ADF4159EB3Z. I set the loop bandwidth for 30 kHz to get my loop filter as shown in fig 3. Fig 1 is my test diagram and fig 2 is the register setting. I can get the output of my VCO at 10 GHz but it is not steady. There is a jitter of the output over 1 MHz range as shown in fig 4.By testing Muxout port, I get DVDD 1.8 V, R Divider Output 100 MHz, R-Divider/2 50 MHz and N-Divider/2 50 MHz. But there is no N Divider Output. I have test the input power of microwave from my VCO to VCO/2 port and it is ~ -1 dBm.

Why the evaluation board EV-ADF4159EB3Z doesn't lock the VCO to 10 GHz?

What should I do next?




Jing Ke