USE DISCOUNT CODEEXPERT30TO SAVE $30 USD
power delivery , signal integrity and layer arrangement
sukru , 12-12-2020, 10:51 AM
I am working with RF design and I have 4 layer Pcb design:
L1=Toplayer with ground pour (2.4GHZ signal)
L2=Ground plane
L3=Signal layer with ground pour
L4=Bottom layer with ground pour
Question 1(POWER PLANE OR POWER POUR?)
On the Picture 1 I share, you see L3 layer. I think I have two option first one using ground pour and spliting it for power just like the Picture 1 I share, second one is using power plane for L3 .Which one is the best solution for signal integrity , EMC and power delivery without loss ?
Question2: (POWER DELIVEY ON SIGNAL LAYER OR POWER PLANE?)
I emphasize the 2.4GHZ trace on Picture2. Is it a good power deliver? or Is it better to keep all the power trace on L3 (power plane or pour)?
Question3 : (BEST LAYER ARRANGEMENT FOR 4 LAYER PCBS)
For the best signal integrity on high frequency what is the best layer arrangement on 4 layer pcb design ? and why?
Question4 : (IF TWO SIGNAL ARE SHARING THEIR RETURN PATH)
L1 - Signal
L2 - GND
L3 - Signal
L4 - GND
L5 - Powers
L6 - Powers
L7 - GND
L8 - Signal
L9 - GND
L10 – Signal
If ı use this layer arrangement, Return path of L3 will be on L2 and L4 .L1’s return path will be on the L2 Is this a problem for the L1 and L3 signal ? because they share same return path.
Question 5: (POWER PLANE RETURN PATH AND SIGNAL RETURN PATH ON SIGNAL-GROUND-POWER ARRANGEMENT STACKUPS)
Return path of the signal on L1 is in the L2( ground plane ) and I use power plane or power pour depend on the answer of the Question 1 where is the return path of this power trace at L3? In bottom layer(L4) or in the L2 ? I ask this question because I wonder that is there a possiblity that power plane return path has a bad effect on the signal return path ?
robertferanec , 12-14-2020, 06:32 AM
I am not an RF expert, so I can't really help with this 
sukru , 12-14-2020, 12:33 PM
@robertferanec thank you for reply.Can you give a general answer for this question instead of RF? because I think that will be quite helpfull for people who want to design High speed with good signal integrity and good EMI/EMC result. And the post includes some return path questions which will be also helpfull for every PCB designers.
qdrives , 12-14-2020, 04:23 PM
Signals should have a corresponding return plane below (or above) it.
Do keep the dielectric thickness between the two low (<= 0.2mm).
A signal of 2.4GHz will not have much skin depth (see Saturn PCB tool) so sharing a single return plane is no problem.
Routed power vs power plane I would say comes down to inductance (impedance) of the connection. Also local decoupling is important. Robert has made plenty of videos about decoupling that would make most heads spin ;-)
Do keep the dielectric thickness between the two low (<= 0.2mm).
A signal of 2.4GHz will not have much skin depth (see Saturn PCB tool) so sharing a single return plane is no problem.
Routed power vs power plane I would say comes down to inductance (impedance) of the connection. Also local decoupling is important. Robert has made plenty of videos about decoupling that would make most heads spin ;-)
sukru , 12-14-2020, 05:03 PM
@qdrives thank you for your answer. Signal-Ground plane-power plane-signal is suitable layout according to what you write. If I am triying to make a power delivery for a small area I can deliver it with using small power pour on L3 instead of big power plane is that a good idea? (also ı will search Robert's videos for decopling thanks for sharing your idea)
qdrives , 12-15-2020, 12:43 PM
What signals are you running on layer 4? What use is the power plane/region if there is no Gnd to reference it?
Rick Hartley had some dat on better 4 layer stackup. Try https://www.google.com/search?q=bett...hrome&ie=UTF-8
Rick Hartley had some dat on better 4 layer stackup. Try https://www.google.com/search?q=bett...hrome&ie=UTF-8
sukru , 12-16-2020, 05:57 AM
@qdrives Layer 4 is the bottom layer with ground pour and all the critical signals are on the top layer. thanks for sharing Rick Hartley's videos which are perfect for understanding the layer arrangement.
Use our interactive Discord forum to reply or ask new questions.