The invention concerns a circuit comprising: a first circuit block (302) adapted to receive a first clock signal (CLK1) and to provide a first output data signal at a time determined by said first clock signal; a second circuit block (304) adapted to receive a second clock signal (CLK2) and to provide a second output data signal at a time determined by said second clock signal; a clock bus (314) coupled to corresponding outputs of said first and second circuit blocks for receiving a third clock signal (BCLK) based on said first and second clock signals; and a synchronization unit (312) coupled to said clock bus and adapted to sample said first and second output data signals based on said third clock signal.