手机的布线问题
从PA到天线的馈点是怎样走线的?各位大虾帮忙哦。
Hi,You better keep it as microstrip line with good grounding.Keep the trace length as short and no 90 degree bend as possible.wilson
Hi,Mr Chen
"no 90 degree bend as possible"
Why?
breeze
不是说要走50 ohm的线么?
你们是自己算出线宽来的么还是有什么经验?如果是算出来的怎么算法啊 ?
因为一般都是6，8层板，怎么去做，如果能有个图来说一下的会很直观的。
从PA出来一直到天线feeding，我发现有许多手机，在这段线上还不一样粗的?奇怪！
PA出来应该是先到FEM再到RF Switch然后还要经过Match才能到antenna吧，你问的是那一段呢?
Hi,
90 degree bending without smoothing will introduce extra capacitance and change slightly the impedance for 50ohm.
Also the sharp edge RF trace is more easier to radiate.
It's possible for RF high energy go in different layers, but pls maintain them on the RF component layer. Because impedance variation is more for inner layer or RCC dielectric. BUT, if the length is short enough from ASM antenna pin to antenna connector, then this is sometimes allowable.
Remember trace that use in the other way than above will not only affect your transmit but also reveive sensitivity ！
Regards,
<P align=right><FONT color=#ff0000>+5 RD币</FONT>
Normally as the other guys said, to keep the length of line as short as possible. The transmission line width and gap to ground plane is calculated or simulated to 50Ohms, but in the reallity, you have to concern about the mechanical constrains such as pad, the soldering and other components. So a perfect 50Ohm line is very difficult to achive.
BR
PA出来应该是先到FEM再到RF Switch然后还要经过Match才能到antenna吧，你问的是那一段呢?老兄不吝赐教，还是都说说吧，实在是不知道阿。要不如果有什么资料可以看的话，给按说一下也好。具体是怎样个布线法?
个人觉得这一段还是走在表层，做成微带线的形状，可以兼顾散热，，线宽。而且在表层比较直观，，比较有经验的工程师可以很直观的看到阻抗线做出的效果。
走线走在表层不好,会造成很大的干扰,影响手机的接受灵敏度
还是走在地线下面的好.
<P align=right><FONT color=red>+3 RD币</FONT>
一般不走表层,这段线要做50ohm;走表层阻抗误差比较大！
楼上兄弟，走在表层怎么会不好呢！下面一层把地做好，上面有屏蔽罩，不会有什么问题。而如果走在内层，的确是上下都会有GND，但是由于最终的器件还是在表层，因而射频线还得要打孔到表层。打孔会对射频信号来说是不好的，尽量避免打孔。
hehe ,孔是90度^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
表层： 阻抗线一般会比较宽，控制的进度会高一点；并且由于表层与第二层间介电常数比较小，一般传输时延小；缺点是EMI问题可能会多一点。中间层：阻抗线相对会窄一点，难于控制，过孔效应大，中间层介电常数大，传输时延大；优点:EMI会好一些。
尽量不要在板面走线，这样对于PCB的生产不利从而对性能有负面的影响。
MSN：xbhjo@sohu.com
如果比较宽就要走表层，免得天线难设计
算阻抗软件是polar吗