How to arrange these layers in the PCB?

[yakex]

Hi,
there are four layers, namely signals, ground, +5V, +9V. but I do not know how to arrange them. please help me.
The amplifier's supply is mainly rounted to +9V, and the +5V is only for RF switch (very little current!). I might have several options
(1) 1st layer: singal
2nd layer: ground
3rd layer: +5V
4th layer: +9V
(2) 1st layer: signal
2nd layer: ground
3rd layer: +9V
4th layer: +5V
(3) 1st layer: signal/ground
2nd layer: ground
3rd layer: ground
4th layer: +5/+9V
I prefer to (2) than (1), but I thought (3) is best!
anybody can help me?
Thank you in advance.

 

[RCinFLA]

I would not waste a layer for 5v RF switch supply.

Supplies can really buck shot the ground plane layer as all supply connections has to be a via all the way through board. If you can do some nearby supply interconnect on top layer to reduce top to bottom vias it helps.

Think of it as two, two layer boards with a filler layer in between. Any connections between the two upper layers to two lower layers have to be a via all the way through, top to bottom, of combination sandwiched boards.

 

[keith1200rs]

It really depends on the circuit and you can only decide when laying it out, but a typical build for me would be

1. Signal
2. Ground
3. Power
4. Signal

Keith

 

[yakex]

Thanks.
I don't need the second signal layer now. what should I do now? Set the bottom layer as ground layer?

 

[keith1200rs]

Yes, or use the two inners as ground. It frequently happens to me - I need 3 layer boards! Usually one layer has very little on it or I just add an extra ground plane.

Keith.

 

[yakex]

Yes, or use the two inners as ground. It frequently happens to me - I need 3 layer boards! Usually one layer has very little on it or I just add an extra ground plane.

Keith.

Many Thanks.

 

[yakex]

I decide to choose the following arragement. anybody has suggestion?

1st layer: signal/ground
2nd layer: ground
3rd layer: ground
4th layer: +5/+9V