What is C-PHY and D-PHY?
C-PHY and D-PHY are physical layer (PHY) standards developed by the MIPI Alliance for high-speed data transmission in mobile devices and other applications. They are used to interface with various components like displays and cameras. The key difference lies in their data encoding and resulting data rates.
- Definition: D-PHY is a simpler, older physical layer standard. It transmits data without encoding, resulting in a lower data rate compared to C-PHY for the same symbol rate.
- Data Rate: Offers 2.5 Gbps per lane of bandwidth (based on D-PHY v2.0). Higher speeds are possible with later versions.
- Applications: Widely used in various applications, including display interfaces (DSI) and camera interfaces (CSI-2).
- Advantages: Its simpler design can lead to lower power consumption and implementation costs in some scenarios.
C-PHY (Camera PHY)
- Definition: C-PHY utilizes data encoding to achieve higher data rates. It packs approximately 2.28 bits per symbol, increasing efficiency.
- Data Rate: Achieves a higher data rate than D-PHY at the same symbol rate because of its efficient encoding scheme.
- Applications: Primarily used in high-resolution camera interfaces where higher bandwidth is essential.
- Advantages: Significantly higher data throughput compared to D-PHY, crucial for handling high-resolution image data.
Key Differences Summarized
| Feature | D-PHY | C-PHY |
|---|---|---|
| Data Encoding | No encoding | Uses encoding (16/7 ≈ 2.28 bits/symbol) |
| Data Rate | Lower at same symbol rate | Higher at same symbol rate |
| Complexity | Simpler | More complex |
| Power | Potentially lower | Potentially higher |
| Applications | Displays, cameras (lower resolution) | High-resolution cameras |
Many modern chips integrate both C-PHY and D-PHY support to offer flexibility depending on the application's bandwidth needs. The choice between C-PHY and D-PHY often depends on the trade-off between data rate requirements and power consumption and implementation complexity.
