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One LTE B7 Desense Case Study
There is a 10 dB difference in sensitivity between the maximum and minimum transmitter power for B7. Removing the B40 PRX matching network eliminates the issue. With insufficient port-to-port isolation, the B7 TX couples to the B40 port and then couples again to the B7 PRX trace from the B40 PRX trace. There are two proposed solutions: using a switch with at least 32 dB of port-to-port isolation or enhancing the trace isolation between the B40 and B7 PRX traces through a layout modification.
One LTE B7 Desense Case Study
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- 2. Transceiver Switch B7_B40 TX B40 PRX HB_PAB7_B40TX B40 TRX B7 TX B7 PRX ASM PRX Matching PRX Matching Introduction For B7, there is 10 dB difference in sensitivity between maximum and minimum transmitter power. And the block diagram is as below: 2
- 3. Introduction Remove B40PRX matching network, the issue disappears. Transceiver Switch B7_B40 TX B40 PRX HB_PAB7_B40 TX B40 TRX B7 TX B7 PRX ASM PRX Matching 3
- 4. Introduction With insufficientport-to-port isolation, B7 TX couples to B40 port, and couples to B7 PRX trace from B40 PRX trace again. Transceiver Switch B7_B40 TX B40 PRX HB_PAB7_B40 TX B40 TRX B7 TX B7 PRX PRX Matching PRX Matching Due to insufficient port-to-port isolation Due to close trace 4
- 5. Introduction Because thecouple path is : we have to two solutions : Change a switch with sufficient port-to-port isolation (at least 32 dB) With layout modification, enhance the isolation between B40 and B7 PRX traces. 5