A hardware-efficient carrier synchronisation technique for multiband RF interconnect system is proposed. This method takes full advantage of the wireline channel's quasi-invariant nature for achieving both energy/cost-efficient system designs. For instance, now easily decouple quadrature signals' phase and magnitude errors by using 1-bit analogue-to-digital converter (ADC), which saves substantial power and area than that of conventional methods where the ADC with highspeed/resolution is necessary. Furthermore, the algorithm can be carried out by using a simple finite-state machine and no baseband processor is required. Simulation and measurement results show that quasiideal carrier synchronisation can be achieved with the proposed method.