This work presents synchronization of two bidirectionally delay-coupled phase-locked-loop (PLL) systems with voltage controlled oscillator frequencies of 24 GHz to validate a non-hierarchical clock distribution approach. For this purpose, a PLL architecture that allows mutual coupling between two such nodes is introduced. An existing phase domain model is extended to include the nonlinear response of the oscillator to the tuning signal. With this extension the frequencies and phase-relations of self-organized synchronized states can be predicted. This is verified by measurements obtained from two synchronized PLLs for different time delays and division factors.