Case analysis of camera power supply disturbed, seriously affecting image quality

about PCB layout For Engineers , Besides rich experience, we must have a solid theoretical foundation , Signal integrity and power integrity are the skills of the family , Otherwise, no matter how skillful the wiring tools are . Want to increase experience , Be sure to have more project support , Step on more holes , Study how to improve the routing quality , More imitations , In order to reasonably plan the layout , Clearly know the impact of each route , Make sure you have a million strong soldiers .

otherwise , Even if you draw a thousand boards without complete constraints , It is no better than drawing a complete board .

Today, we share a pit related to analog power supply .

There are thousands of components on the mobile phone , Thousands of networks , Nearly 100 power supplies , Radio frequency should be compressed into the small board 、 The antenna 、 simulation 、 High speed 、PDN、 Charge 、 Audio and other modules are very difficult work

So much content can not be completed by one person in a short time , This requires strong team support . Buddy is one of them , The load carries out secondary review on the wiring , Make up the knife , Today we will introduce a pit related to analog power supply , Brother, failed to mend the knife , All blood and tears .

The background of the incident is that the image quality of the camera does not meet the internal standard , From the user's point of view , There is noise in dark light photography . The positioning method is not complicated , Provide external power supply for each power supply of the camera , Finally, it was found that the analog power supply of the camera was abnormal , If an external power supply is used to supply power to the camera nearby , The image quality is normal , Power supply near the power source is abnormal , Enter below .

therefore , The analysis of the problem becomes the problem of the camera analog power supply ？

Analog power supply is always sensitive , It's also layout The key care objects of engineers and brothers , I guess there is probably a big power disturbance nearby , I asked for some drawings , I checked it myself .

ha-ha , Sure enough , There is a section in the middle of the analog power supply , Next to it is a large current BUCK Power plane ,BUCK The interference during operation is coupled to the analog power supply of adjacent cameras , And then affect the image quality of the camera , This interference is too small , Ordinary electrical tests cannot find , But it will affect the image quality , Similar to the figure on the right .

（ chart ：LinsonW）

So why didn't you find it out in the early stage ？ There is no absolutely safe system in the world , Even if a person is careful, he will miss something , It is estimated that there are too many times to check , The routing is frequently modified , Fall into habitual thinking , Just check it too many times , I'm in .

At this time , A complete R & D process begins to show its value ： Even if PCB layout The engineer did not find the problem , There are also special personnel for secondary review , If no problem is found in the second review, the module leader will also test the module , Intercept the problem again , Until the whole machine is tested and intercepted again , Under multiple checks , Problems are easily exposed .

Brother, the problem was intercepted with the help of brother departments .

So how to modify ？ The best solution is to move the power cable directly , But the cell phone is a place , stretched , Pull one hair and move the whole body .

The final choice is to use ground wire for isolation , After modifying the hair board, my friend has been having trouble sleeping and eating , Worry about other effects , This cautious attitude , I agree with you very much .

When the board came back, everything was normal , Now, my friend can rest assured , I slept soundly , The food is also happy , In one breath 5 Building is easy .

Analog signal and power supply PCB The routing must not be careless , Today's small class of watching the sea mining pit is shared here , Which pits have you stepped on ？ Feel free to leave a comment .