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This lesson talks about the connection channels of the 4G frequency band

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of the three major platforms in the circuit diagram,

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how HiSilicon, MediaTek, and Qualcomm reflect the receiving

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and transmitting channels of the 4G frequency band of the mobile phone in the drawings

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Let's look at the Huawei P40 first

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Open this Xinzhizao maintenance query system, find the model of P40, and find its schematic diagram

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After opening the schematic, you can find it from its antenna

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This is the transceiver channel of the RF circuit in the B3 frequency band of the P40

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Antenna is J5607

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The reception is from the outside to the inside.

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After the electromagnetic wave in the air is converted into an electrical signal by the antenna, it is given to the filter,

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and then the filter is given to the single-pole 4-throw switch.

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After passing through this switch, the received signal continues to go to the filter

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After filtering out the clutter, an intermediate frequency band transceiver signal is formed,

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which is sent to the 36 pin of the antenna switch

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Come out from pin 27 to form the receiving signal of the B3 frequency band

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Continue to go through the inductor and go to the receiving amplifier, which amplifies its electric power

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After amplification, output and receive signals from A4 A6 A8 pins

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The received signal reaches the RF transceiver, which mixes it

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USR_DL signal is formed after mixing

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This downlink is the reception of the mobile phone

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This downlink signal is sent to the big CPU

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The large CPU contains a baseband CPU

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The baseband CPU demodulates the downlink signal,

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and finally restores the video and picture information, as well as some data

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For the receiving channel, we can find the CPU.

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This is its receiving line

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The emission line can also be searched from its CPU

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The AD5 pin of the CPU outputs the UL signal, that is, the emission signal

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The uplink signal is sent to the RF transceiver, mixed by the RF transceiver,

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and becomes a transmitted high-frequency signal

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This mid-band line transmits the signal and continues to go to the power amplifier

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The power amplifier amplifies the power of the transmitted signal, and then outputs it from pin 25

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It becomes the transmission signal of the B3 frequency band

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The signal reaches the 8th pin of the antenna switch U4801 through the inductor

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Antenna switch conducts pin 8 and pin 36 under controlled conditions

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Pin 36 is a line connected to the antenna end, pin 8 is the transmitting signal

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This switch acts as a conduction

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At this time, the transmitted signal passes through the filter Z4801

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to filter out the clutter and reaches a double-pole four-throw switch

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This switch has multiple antenna inputs and multiple line outputs, so it is called double-pole four-throw

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The signal comes out from pin 3, passes through the filter Z5603 to filter out the clutter, outputs from pin 3,

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and reaches the first pin of the antenna base J5607

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There is an antenna installed on the antenna base

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The antenna turns this high-frequency signal into a high-frequency electromagnetic wave

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and transmits it to the base station

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This is the transceiver channel of the radio frequency circuit of Huawei P40 frequency band

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That's all for this lesson