Design Article
MIPI M-PHY takes center stage
Ashraf Takla, Mixel Inc. and George Brocklehurst, Nanotech Semiconductor
11/13/2010 11:37 PM EST
The Character of the M-PHY
The M-PHY is defined as a serial link. The overall objectives fall into this general requirements list:
Since the M-PHY is meant to replace the D-PHY in applications that require higher throughput, systems designers will have a choice as to which physical interface to use. Table 1 highlights the differences between the D-PHY and M-PHY, and Figure 1 shows the location of the camera /and display subsystems linked by either the D-PHY or M-PHY interconnections.
Next: The Stage and Script
The M-PHY is defined as a serial link. The overall objectives fall into this general requirements list:
- Low pin count: all control signalling handled in-band across the interface
- Supports both electrical and optical interfaces using low complexity electro-optical signal conversion
- Optical friendly electrical specification (sufficient timing flexibility, DC balanced coding scheme, etc)
- Optimized for short distance (<10cm) but suitable for long-distance (m)
- Huge range of speed requirements: ~10Mbps to ~6Gbps
- Power efficient throughput adaptation using burst-mode
- Clocking: shared or non-shared reference clocks
- Independent of foundry process
- EMI friendly
- Multiple transmission modes for better power efficiency
- Multiple transmission speed ranges/rates for varied application needs and for mitigation of interference problems
- Fixed transmission rates for high-speed mode but flexible for low-speed modes within specified ranges
- Multiple power saving modes, where power consumption can be traded-off against recovery time
- Symbol coding (8b/10b) for spectral conditioning, clock recovery, and in-band control options for both PHY and Protocol level
- Configurability to reduce cost and tuneable for best performance
Since the M-PHY is meant to replace the D-PHY in applications that require higher throughput, systems designers will have a choice as to which physical interface to use. Table 1 highlights the differences between the D-PHY and M-PHY, and Figure 1 shows the location of the camera /and display subsystems linked by either the D-PHY or M-PHY interconnections.
Figure 1: Inside of a mobile phone showing an example of MIPI connections between the application processor and camera and display subsystems. Connections made using a D-PHY or M-PHY (source: Mixel, Inc.)
Table 1: Comparison of the characteristics of the MIPI’s D-PHY and M-PHY (Source: Den Besten, Gerrit of NXP)
Table 1: Comparison of the characteristics of the MIPI’s D-PHY and M-PHY (Source: Den Besten, Gerrit of NXP)
Next: The Stage and Script
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