Refer to HMC778 evaluation board, I have made a PLL board and its schematic is shown below. The RF output power of hmc778 should be 9dbm@10GHz. And I want to get 9-5+14=18dbm output power through a attenuation network and PA hmc441.
The problem is the output power of hmc778 only reaches 2dbm@10GHz. So when I use a 100pF capacitor to replace the attenuation network, total output power reaches 16dbm@10GHz. Do you know any possible reasons that could cause the decrease of output power?
The RFOUT signal is correctly locked with REFRF signal.