power supply requirement for cyclone II

[Altera_Forum]

we are in design process for our new design using cyclone II series FPGA, 

 We have a doubt regarding a power supply requirements.    In EP2C5 datasheet it is given that 1.2V as AVDD(analog supply)  and another 1.2 V as DVDD(digital supply), our question is whether      we can use single 1.2V supply for Avdd and DVdd or we have to use seperate 1.2V supplies.     Waiting for your reply

[Altera_Forum]

You should implement the suggested passive filtering for PLL supply VCCA. Some development kits actually use a separate voltage regulator for VCCA, but I never used it. You should consider however, that besides high frequency interferences also mid frequency ripple of the PLL supply can cause excessive jitter and even loss of lock.