The LCFI Collaboration is developing the sensors, readout electronics and mechanical support structures for the Vertex Detector (VXD) of the International Linear Collider (ILC). High-speed readout is needed to ensure that the occupancy due to the pair production background at the ILC is kept below 1% level. In order to satisfy this requirement, Column Parallel CCDs (CPCCDs) and Column Parallel Readout chips (CPRs) have been developed. The CPCCD has to operate at a clock frequency of 50MHz, which represents a difficult technical challenge due to the relatively large sensor capacitance. The design and performance of planar transformers, which can be used to provide the required 20A clock current, are described.