An RF circuit for providing phase coherent signals, an RF heating apparatus comprising the RF circuit and a method for providing phase coherent signals in an RF circuit. The RF circuit has a first frequency synthesiser including a fractional-N phase locked loop and a second frequency synthesiser including an integer-N phase locked loop. An output of the first frequency synthesiser is connected to a phase frequency detector of the integer-N phase locked loop of the second frequency synthesiser via a synchronization signal divider for distributing a synchronization signal from the first frequency synthesiser to the second frequency synthesiser. The integer-N phase locked loop of the second frequency synthesiser comprises a frequency divider of the same modulus as the synchronization signal divider.