Optimizing Phase Noise in 9GHz Design with STUW81300

Hello, I’m working on creating a 9GHz design with excellent phase noise using the STUW81300. The reference frequency is 50MHz, and the PDF is also 50MHz, with a single-ended configuration.

To design the loop filter, I utilized STWPLSim v5.3. However, upon comparing the actual measurements with the simulated values, I noticed a discrepancy of 3 to 7 dB. The settings appear to be correct, and I’m seeking advice on whether this difference is normal or if there’s an issue with the design.

Simulation Results

• -81dBm/Hz at 100Hz offset
• -94dBm/Hz at 1KHz offset
• -102dBm/Hz at 10KHz offset
• -106dBm/Hz at 100KHz offset
• -124dBm/Hz at 1MHz offset

Measurement Results

• -77dBm/Hz at 100Hz offset
• -88dBm/Hz at 1KHz offset
• -95dBm/Hz at 10KHz offset
• -103dBm/Hz at 100KHz offset
• -120dBm/Hz at 1MHz offset

I would appreciate any guidance on this matter, as I’m unsure whether the discrepancy is within normal limits or if there’s a problem with the design.