Serializer circuitry for high-speed serial data transmitters on programmable logic device integrated circuits

Serializer circuitry on an integrated circuit comprising:

• a plurality of channels of serializer circuitry, each of which employs a high frequency clock signal and a low frequency clock signal;
• a plurality of phase locked loop circuits, each of which can produce a respective one of a plurality of reference clock signals;
• global clock generator circuitry for using one of the reference clock signals to produce a global high frequency clock signal and a global low frequency clock signal;
• first selection circuitry associated with each of the channels for selecting one of the reference clock signals;
• local clock generator circuitry associated with each of the channels for using the local reference clock of that channel to produce a local high frequency clock signal and a local low frequency clock signal;
• and
• second selection circuitry associated with each of the channels for selecting either the global high and low frequency clock signals or the local high and low frequency clock signals of that channel for employment by that channel as its high and low frequency clock signals.