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This lesson talks about the channel of the 4G frequency band of OPPO mobile phones

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Here we take the OPPO R15 model circuit as an example

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Because OPPO's drawings are only up to R15, there are no more drawings for phones after R15

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What about repairing the radio frequency circuit of OPPO mobile phones?

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If you use a Qualcomm processor, you can refer to Xiaomi and Huawei.

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The most complicated radio frequency is Huawei's

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If you can understand Huawei's, then OPPO's is relatively simple

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Let's take a look at the inside of this phone, first look at its reception

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The reception is the signal coming from the direction of the antenna.

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The antenna induces the high-frequency electromagnetic wave in the air into a high-frequency electrical signal,

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forming a receiving signal to the normally closed contact

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The normally closed contact is called CN 1001 in its drawing

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The receiving signal enters from its second pin and comes out from the first pin

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Receive the signal and keep going until you reach a double pole double throw switch

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Double-pole double-throw switch two-pin and four-pin conduction

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Because it's just a switch, a controlled switch

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That is, the conduction of the two feet and the four feet is controlled,

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and is controlled by the control signal of the nine feet.

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Then after 2 and 4 are turned on, the receiving signal continues to go,

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and the antenna switch that reaches the low, medium and high frequency bands is called U1108

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It reaches pin 22, which is the antenna end

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What is the purpose of the receiving signal arriving inside?

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It is the antenna switch, which is a switch for signals in each frequency band.

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When the received signal arrives here, the internal switch turns on pin 22 and pin 26

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The receiving signal continues to go, forming the receiving signal of the 41 frequency band received by the main set

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This received signal reaches one leg of the filter U1212

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After filtering the clutter, go out from pin 9

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After going out, reach the fifth pin of the receiving chip

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The receiving chip amplifies the power of this signal, and outputs it from pin 3 after amplification.

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It continues to go and reaches the A11 pin of the RF transceiver MT6177

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Then the RF transceiver mixes it

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Because you have such a high-frequency signal, your high-frequency part is not needed by the circuit at this time

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What I want is this picture and video information in you

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After the RF transceiver mixes the signal, it sends the processed signal to the large CPU through the IQ bus

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In fact, we can only run to the radio frequency when we run the map.

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The transmission between the radio frequency and the large CPU

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or the baseband CPU is either through the IQ bus or the Qlink bus

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This is the receiving signal channel

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Let's look at its launch channel

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When transmitting, the baseband CPU sends the transmission data to the RF transceiver through the IQ bus

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The RF transceiver mixes the low-frequency signal, and forms a high-frequency band signal after mixing,

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and outputs it to the third pin of the low, medium, and high-band power amplifier,

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and outputs it from pin 39 after power amplification

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It is filtered out by the filter once, four pin in and one pin out

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After that reach this low-mid-high-band antenna switch

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The 27th pin of the antenna switch is connected to the 22nd pin, and the transmission signal is turned on.

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Then the transmission signal continues to go through the conduction of pin 4 and pin 2,

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and reaches the normally closed contact

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Pin 1 and pin 2 of the normally closed contact are always on

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The transmitted signal will continue to go and reach the antenna end

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The high-frequency transmitted electrical signal is converted into high-frequency electromagnetic waves

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by the antenna, radiated into the air, and received by the base station

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This constitutes a complete channel for receiving and transmitting, and the 4G signal can be normal

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This is the frequency band channel of OPPO's 4G

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That's all for this lesson