The reason why the mobile phone signal blocker amplifier has the conduction stray of the shield
The cell phone signal blocker amplifier has the conduction stray of the shield cover. Many users do not understand the cause, but the signal shielding of the equipment is reduced, so the reason, verification method and solution method of the decline are introduced to help users better carry out product use.
1. The matching components are affected by the Shielding Cover so that the impedance is biased
If the Shielding Cover is too close to the matching component, its parasitic effect changes its inductance or capacitance value so that the impedance changes, then of course the conducted harmonics will become larger, especially the early 0402 components are more likely to do this, but now 0201 components rarely do this.
2. RF signal leaks to Vcc of PA
When you cover the shield, the PA will radiate or couple the RF signal to the top of the shield, which means that there will be residual TX signals above the shield. If the shield is well grounded, these residual TX signals will flow to the GND, if the shield is well grounded, some of these residual TX signals will flow to GND, and some will be reflected again. If the reflected TX signal hits the Vcc of the PA, then of course the TX performance will be degraded.
3. The parasitic effect between the shield and the PA too close to the PA changes the PA characteristics.
Ways of identifying :
One is very rare now, so I won't mention it.
In the second case, it can be verified like this
Because you said that the conduction stray will be better without the shield, so if you use this method to make the conduction stray as bad as when the shield is added, then the murderer may be from this reason
It is worth noting that the DC Block should be added to prevent the DC power supply of Vcc from being recharged to the PA or CMW500
solution:
One is very rare now, so I won't mention it.
In the second case, because the murderer is from the RF signal poured into Vcc, so you place a ground capacitor on the Vcc side, so that the RF signal poured into Vcc flows to GND.
Since your main frequency is DCS, in terms of 0201 capacitors, you should put 18 pF.
Three types of institutions can only be changed
Either increase the distance between the shield and the PA, or open the skylight directly above the PA.
The above is the introduction of the reasons for the phenomenon that the mobile phone signal shield amplifier has the conduction stray of the shield cover. According to its introduction, it can help users to use the equipment better, so as to achieve its specified use efficiency.
