Dear Support member
The customer is to improve GPS receiver sensitivity on a system using DS90UB953.
A GPS module is implemented in the camera module.
The IMX390 (SONY image sensor) in the camera module is connected to the DS90UB953.
The GPS module has sufficient reception sensitivity.
When the IMX390 is operated, the C/NO value deteriorates by about 20 dBHz.
The IMX390 is set to Full HD (1080p) 20 Bit multi-exposure raw data at 30 FPS.
At this time, data rate is 371.25Mbps/lane × 4-lane.
This is the input to MIPI in DS90UB953.
When it is output from DOUT+ and DOUT- on the DS90UB953, it will be about 1485 Mbps (742 MHz) because it is added by 4-lane.
The frequency received by the GPS is 1575.42 MHz.
I assumed that the 2 times higher harmonic is close to the reception frequency of the GPS and is a noise factor.
Looking for the noise source with a loop antenna, we found that the noise level of the filter (PCMF3USB3S/CZ) where DOUT+ and DOUT- of the DS90UB953 are connected is high.
We tried to reduce the noise by adding a capacitor (22p) and beads (100 MHz, 120 Ω), but it was not an effective measure because it affected the FPD Link signal or was ineffective.
Q1.
If you have know-how on noise reduction (reference materials, etc.), please let me know.
Q2.
Please tell me if there are any noise reduction parts recommended for the FPD Link signal.
Best Regards,
