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This lesson is about the transceiver channel of the radio frequency circuit of Huawei P40 B3 frequency band

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Open the drawing, this is the drawing of Huawei P40

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According to this framework, first find its antenna

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Its antenna is called J5607

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We searched for this antenna in the drawings

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This phone has a lot of antennas inside

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So why are we looking for this antenna

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It's because of this antenna mount we look to the left

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After the signal from this antenna passes through the inductor, its English definition is MHB

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MHB is mid-band and high-band

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Here we need to find B3, B3, they belong to the middle frequency band

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So this antenna must have passed the B3 frequency band

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Both receiving and transmitting go from here

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Let's see its reception first

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After the antenna turns this high-frequency electromagnetic wave signal

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into a high-frequency electrical signal, the name becomes this M H B

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Let's see where this receives it next

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Enter it into the search box and click Next

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He got to the three pins of this filter Z5603

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Receive is three feet in, one pin out

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After the received signal passes through the filter to filter out the clutter,

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it passes through the inductor, and then passes through the frequency selection of the capacitor.

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After frequency selection, it becomes D P 4T, which is a double-pole four-throw switch

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It went over a small switch

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We type it into the search box

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Through searching, it is found that it reaches the third pin of the chip U5601

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This is the received signal

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Receive signal goes up to this DP4T switch

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Its pins 3 and 11 are external, that is, it is connected to an external antenna

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Then pins 1, 16, 14 and 13 are docked in the board

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This received signal is the received signal of B3

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The mid-band actually has two channels

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One pin comes out of the channel, which is the receiving signal

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Because this is an antenna signal, the antenna signal is received and transmitted

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There is also a channel in the mid-frequency band that comes from 14 feet, M B BYPASS is called bar T R X

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Let's find one of the channels first

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C A is the antenna signal of the medium and high frequency band coming out from one foot

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The receiving signal of B3 will be turned on through the switch

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Let's see where it leads next

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Search for this signal, it goes to pin 2 of the filter Z4801

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This is the public end

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After filtering out the clutter, he passed the inductance and capacitance

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The receive signal goes to pin 36 of this chip

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This chip is an antenna switch for medium and high frequency bands

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It is responsible for the reception and transmission of all frequency bands

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The antenna signal comes in, then the receiving signal and the transmitting signal are separated

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At this time we are looking for the receiver of B3

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Pin 27 is B3 R X, this is the receiver of B3

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We search for it

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After arriving here, it comes in from pin 36 and connects to pin 27

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through the conduction of the internal switch to form the receiving signal of B3

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The receiving signal continues to go after reaching the inductor

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Its English becomes PRX_B3

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We search the name to see where it goes

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It reached the D1 pin of a chip

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LNA is the receiving amplifier

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The receiving signal comes in from the first pin and reaches the D1 pin of the chip U5201

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That's all for this lesson