DLM0QSN500HY2
Noise suppression technologies/case study introduction (Consumer)
Noise Suppression for MIPI D-PHY
INDEX
- What is MIPI D-PHY?
- Noise Suppression for MIPI D-PHY
- Measures for suppressing noise for MIPI D-PHY
- Notes on Noise Suppression for MIPI D-PHY
- Noise filters for noise suppression for MIPI D-PHY
- Example of noise suppression effect
- Example of effect on differential signal waveform (Use of DLM0QSN500HY2)
- Conclusion
1. What is MIPI D-PHY?
MIPI D-PHY is an interface standard used in the exchange of signals for displays and cameras within a mobile device.
In version 2 of D-PHY, communication speeds of up to 4.5 Gbps per lane are possible. This technology supports the greater volumes of video data that are occurring due to the higher resolutions in smartphones and other mobile devices.
A C-PHY standard is also available, and it enables communication speeds of up to 6 Gbps per lane.
For details on noise suppression for C-PHY, refer to this document.
- Usage Applications(LCD-CPU, Camera-CPU)
2. Noise Suppression for MIPI D-PHY
Noise is emitted from the FPC cable by digital signals that pass through MIPI D-PHY lines between the main board and module, and this noise can enter the antenna in the wireless circuit, which can result in reduced reception sensitivity of the antenna. For this reason, noise passing through MIPI D-PHY lines must be removed.
3. Measures for suppressing noise for MIPI D-PHY
A noise filter is inserted into the interface section of the main board for reducing the outflow of noise to the FPC cable.
4. Notes on Noise Suppression for MIPI D-PHY
Example of noise suppression in conventional interface
Conventional interfaces were either differential transmission systems or single-ended systems.
- Differential transmission line → Common mode choke coil
- Single-ended transmission line → LC filter, etc.
No issues arose when usage was divided as shown above.
However, in MIPI, differential signals and single-ended signals are mixed.
→ This requires a noise suppression method that does not affect the waveforms of both high-speed differential and single-ended signals.
5. Noise filters for noise suppression for MIPI D-PHY
The following common mode choke coils and noise filters are recommended for MIPI D-PHY version 2.0. These minimize the effect on both differential and single-ended signals for reducing common mode noise.
| Part Number | Search inventory |
Size [mm] |
Effective frequency band | |||
|---|---|---|---|---|---|---|
| 700M-900MHz LTE/GSM |
1.5GHz-2.6GHz LTE/GSM |
2.4GHz Wifi/BT |
3.5GHz LTE |
|||
| DLM0QSN500HY2 |  |
0605 | ○ | ○ | ○ | |
| DLM0NSN500HY2 | |
0806 | ○ | ○ | ○ | ○ |
6. Example of noise suppression effect
7. Example of effect on differential signal waveform (Use of DLM0QSN500HY2)
Inserting a filter has no negative effect on the signal waveform.
8. Conclusion
In mobile devices, noise emitted from the MIPI D-PHY interface used in connections between displays and cameras can enter the antenna of the device and reduce the antenna sensitivity. One effective measure for preventing this noise is to use a common mode choke coil and noise filter at the interface outlet.
Because the MIPI D-PHY uses both differential signals and single-ended signals, care must be taken to select a component that does not distort the signal waveforms.
Use of the common mode choke coils and noise filters described below is recommended.
Filters recommended for noise suppression for MIPI D-PHY
| Part Number | Search inventory |
Size [mm] |
Effective frequency band | |||
|---|---|---|---|---|---|---|
| 700M-900MHz LTE/GSM |
1.5GHz-2.6GHz LTE/GSM |
2.4GHz Wifi/BT |
3.5GHz LTE |
|||
| DLM0QSN500HY2 | |
0605 | ○ | ○ | ○ | |
| DLM0NSN500HY2 | |
0806 | ○ | ○ | ○ | ○ |
References:
Noise Suppression for MIPI C-PHY
Selection chart for common mode choke coils and noise filters for MIPI D-PHY
