timer000
Newbie level 4
Hello everyone, I am a rookie in RF, May I know how many metal shields are needed when using multiple PAMIDs in a 5G phone?
Some layout guides mention that each PAMID needs a metal shielding, but I saw some design doesn’t follow it.
Regarding the metal shielding of PAMID, my personal guess is as follows.
Please correct me if I am wrong,
1.I thought that between TX signals, because the TX signal is strong enough (maybe 20dBm) 5G PAMID (whether it is LB/MHB/UHB), generally will not interfere with each other, (maintain the 3W rule)
2.But based on the consideration of heat generation when PA is operating, PAMID needs to keep a distance from each other (I personally think 9mm is a safe distance, but is it possible to have a shorter distance?
3.I thought that the meaning of PA using shielding is to block the cross-talk of TX trace to RX trace(including TX signal, IM 2&IM3 cross-talk and Vco-pulling) Is this understanding correct?
4.PAMID or other non-linearity components may produce IM2, IM3 between each other. After transmission, it interferes with the RX signal of another antenna’s LTE/5G/GPS through the antenna. This can not be blocked by shielding, and needs to be processed by filter or keeping the distance between the two antennas, Is this understanding correct
5.Some PAMID/LPAMID have built-in shielding (maybe a layer of metal coating is applied outside the module) Does this kind of PAMID still need independent shielding? I am worried that its isolation is not as good as the general metal shielding
6.After thinking about it, I think that some PAMIDs that can be in the same shielding case, There may be the following combinations
A.UHF PAMID and LB PAMID (Because the two may not work at the same time, or the IM2/IM3 produced by the two have no effect on The rest of BAND)
B.LFEM (including UHF/LB/MHB) and UHF PAMID (because the frequency difference is too far, and UHF working mode is TDD)
C. As above, whether UHF PAMID can be placed in the same case with 5G IC, I don’t know if it will bring a VCO pulling problem. I ask it because I have seen some designs that put them in the same case.
D. In practice, MHB PAMID needs independent shielding, because it easily produces an IM2 and IM3 with other synchronized working other BANDs. Is this correct?
If I said anything wrong, please correct me.
I appreciate your help.
Some layout guides mention that each PAMID needs a metal shielding, but I saw some design doesn’t follow it.
Regarding the metal shielding of PAMID, my personal guess is as follows.
Please correct me if I am wrong,
1.I thought that between TX signals, because the TX signal is strong enough (maybe 20dBm) 5G PAMID (whether it is LB/MHB/UHB), generally will not interfere with each other, (maintain the 3W rule)
2.But based on the consideration of heat generation when PA is operating, PAMID needs to keep a distance from each other (I personally think 9mm is a safe distance, but is it possible to have a shorter distance?
3.I thought that the meaning of PA using shielding is to block the cross-talk of TX trace to RX trace(including TX signal, IM 2&IM3 cross-talk and Vco-pulling) Is this understanding correct?
4.PAMID or other non-linearity components may produce IM2, IM3 between each other. After transmission, it interferes with the RX signal of another antenna’s LTE/5G/GPS through the antenna. This can not be blocked by shielding, and needs to be processed by filter or keeping the distance between the two antennas, Is this understanding correct
5.Some PAMID/LPAMID have built-in shielding (maybe a layer of metal coating is applied outside the module) Does this kind of PAMID still need independent shielding? I am worried that its isolation is not as good as the general metal shielding
6.After thinking about it, I think that some PAMIDs that can be in the same shielding case, There may be the following combinations
A.UHF PAMID and LB PAMID (Because the two may not work at the same time, or the IM2/IM3 produced by the two have no effect on The rest of BAND)
B.LFEM (including UHF/LB/MHB) and UHF PAMID (because the frequency difference is too far, and UHF working mode is TDD)
C. As above, whether UHF PAMID can be placed in the same case with 5G IC, I don’t know if it will bring a VCO pulling problem. I ask it because I have seen some designs that put them in the same case.
D. In practice, MHB PAMID needs independent shielding, because it easily produces an IM2 and IM3 with other synchronized working other BANDs. Is this correct?
If I said anything wrong, please correct me.
I appreciate your help.
