FPGA_LAYOUT

Designed PCB layout of FPGA using orcad software which consist of 144 FPGA XILINX BASED IC , also 16 bit programmable DAC , 16 bit programmable ADC, Keypad, Display(16x2), USB Port, power supply module, 8-LED & 8 Switches 

Variety of data sheets have been used.

Consideration is given for EMIC as well.

PCB layer stackup (the ordering of the layers and the layer spacing) is an important factor in determining the EMC performance of a product. A good stackup will produce minimal radiation from the loops on the PCB (differential mode emission), as well as the cables attached to the board (common-mode emission). However, a poor stackup will cause excessive radiation from both of these mechanisms.

The following four factors are important with respect to board stackup:

 The number of layers

 The number and types of planes (power and/or ground)

 The ordering or sequence of the layers

 The spacing between the layers

In deciding on the number of layers, the following should be considered:

 The number of signals to be routed and PCB cost.

 Clock frequency.

 Will the product have to meet Class A or Class B emission requirements?

 Will the PCB be in a shielded or unshielded enclosure?

BOARD OBJECTIVE :

1. A signal layer should always be adjacent to a plane.

2. Signal layers should be tightly coupled (close) to their adjacent planes.

3. Power and ground planes should be closely coupled together.

4. High-speed signals should be routed on buried layers located between

planes. The planes can then act as shields and contain the radiation from the high-speed traces.

5. Multiple-ground planes are very advantageous, because they will lower

the ground (reference plane) impedance of the board and reduce the common-mode radiation.

6. When critical signals are routed on more than one layer, they should be confined to two layers adjacent to the same plane.