PLL Phase Shifting design

The purpose of this design is to allow the phase bumping of a PLL as specified in AN367: Implementing PLL Reconfiguration in Stratix II Devices http://www.altera.com/literature/an/an367.pdf. The major differences being:

- This design only allows for phase bumping of the PLL as described on pages 8-11 of AN367

- This design does not require the use of the altpll_reconfig megafunction as described in AN367, just a simple register interface

- This design only uses logic for storage of the PLL configuration bits (< 20 registers and 40 ALUTs); no RAMs or ROMs are used