Hello,
Hope you are doing well.
What is the power configuration you are using in your design? And how are you powering VDD_RF?
Please see AN13831 KW45/K32W148 - Power Management Hardware section 3 "KW45/K32W148 power configurations" for the most common power configurations and considerations.
Note that any power configuration required by your application must comply with the DC voltage requirements for each power domain, which is specified in section 2.2 "Power domain rates"
The internal regulator output is given by VDD_CORE/VOUT_CORE, while the regulator input is given by VDD_CORE. It is highly recommended to connect the pins externally along with the appropriate decoupling capacitors in order to provide a feedback path and maintain voltage stability.
You can find our Minimum BoM Presentation for the recommended capacitor values and other hardware recommendations under this post: The best way to build a PCB first time right with KW45 (Automotive) or K32W1/MCXW71 (IoT/Industrial)
You could also confirm your schematic design by reviewing it with our KW45-EVK schematics.
Best Regards,
Ana Sofia.