My PCB design for Cyclone II ep2c20F484;ep2c35F484

Thank you for suggestions !

I thought that grounding would be a problem but in thouse ALTERA Power supply articles like http://www.altera.com/support/devices/powe...-integrity.html (http://www.altera.com/support/devices/power/integrity/pow-integrity.html)

there is text of that article ''Designers should add as many 0.2 µF power-supply decoupling capacitors as possible to the VCCINT, VCCIO, and ground pins/planes. Ideally, these small capacitors should be located as close as possible to the device. Designers can decouple each VCCINT or VCCIO and ground pin pair with a 0.2-µF capacitor. If a design uses high-density packages such as ball grid array (BGA) packages, it may be difficult to use one decoupling capacitor per VCCINT / VCCIO and ground pin pair. In such cases, designers make every effort to use as many decoupling capacitors as allowed by the layout. Decoupling capacitors should have a good frequency response, such as monolithic-ceramic capacitors.''

In this FBGA 256 PCB designe http://theonlyway.net/eoz/upload/attachmen...76&d=1153473055 (http://theonlyway.net/eoz/upload/attachment.php?attachmentid=676&d=1153473055)

I have place for 9 ceramic capacitors on the Bottom layer for VCC INTernal and For VCC IO I have place for 8 ceramic capacitors on the top layer isn't that enough for EP2C20F256 device if these capacitors are 0.1-0.2uF.

Until now I planed to place in my big FBGA484 PCB desine these small 0.1-0.2uF capacitors as meny as posible in 4th bottom leyer (under FPGA), or I need to make 6 layer PCB 5th layer could be VCC and 6th layer GND.

I planed to use LM2679 ADJ 1.2V 5A Step-down Voltage regulator for internal power supply and for I/O LM2673 3.3V 3A Step-down Voltage regulator as in National Altera designe guide pdf for cyclone FPGA.