M-PHY
{{short description|Data communications physical layer protocol}}
{{Infobox computer hardware bus
| name = M-PHY
| fullname = MIPI M-PHY
| image =
| image_size =
| alt =
| caption =
| invent-date = 2011
| invent-name = MIPI Alliance
| super-name =
| super-date =
| replaces = D-PHY
| width = 1–4 lanes, w/adaptive discovery (depending on higher-level protocol)
| numdev =
| speed = up to 11.6 Gbit/s per data lane
| style = serial, embedded clock
| hotplug =
| external = yes, with optical media converter
| website = https://mipi.org/specifications/m-phy
}}
M-PHY is a high speed data communications physical layer protocol standard developed by the MIPI Alliance, PHY Working group, and targeted at the needs of mobile multimedia devices.{{cite web|url=https://www.edn.com/design/microwave-rf-design/4210711/MIPI-M-PHY-takes-center-stage |title=MIPI M-PHY takes center stage |publisher=EDN |date= |accessdate=2018-04-22}} The specification's details are proprietary to MIPI member organizations, but a substantial body of knowledge can be assembled from open sources. A number of industry standard settings bodies have incorporated M-PHY into their specifications including Mobile PCI Express,{{cite web|url=https://www.edn.com/electronics-blogs/eye-on-standards/4418365/M-PCIe---Goin--mobile- |title=M-PCIe – Goin' mobile! |publisher=EDN |date= |accessdate=2018-04-22}}{{cite web|url=http://eecatalog.com/pcie/2012/10/31/pcie-follows-usb-3-0-to-mobile-applications/|title=PCIe Follows USB 3.0 to Mobile Applications - PCI Express|website=eecatalog.com}}{{cite web|url=http://eecatalog.com/pcie/2013/02/26/pci-sig-and-mipi-alliance-announce-mobile-pcie-m-pcie-specification/|title=PCI-SIG and MIPI Alliance Announce Mobile PCIe (M-PCIe) Specification - PCI Express|website=eecatalog.com}}{{cite web|url=http://www.tomshardware.com/news/M-PCIe-M.2-PCIe-3.1-PCIe-4.0-OCuLink,23259.html|title=PCIe for Mobile Launched; PCIe 3.1, 4.0 Specs Revealed|date=28 June 2013|publisher=}}{{cite web|url=https://pcisig.com/sites/default/files/files/PCI-SIG%20and%20MIPI%20Alliance%20Announce%20Mobile%20PCIe%20(M-PCIe)%20Specification.pdf |title=Specifications |website=pcisig.com }}{{cite web|url=https://www.design-reuse.com/articles/33608/moving-pci-express-to-mobile-m-pcie.html|title=Moving PCI Express to Mobile (M-PCIe)|website=Design And Reuse}}{{cite web|url=https://www.mindshare.com/Learn/Mobile_PCI_Express_(M-PCIe)|title=MindShare - Mobile PCI Express (M-PCIe) (Training)|website=www.mindshare.com}} Universal Flash Storage,{{cite web|url=https://www.jedec.org/standards-documents/focus/flash/universal-flash-storage-ufs|title=Universal Flash Storage (UFS) - JEDEC|website=www.jedec.org}}{{cite web|url=https://www.design-reuse.com/articles/30845/universal-flash-storage-mobilize-your-data.html|title=Universal Flash Storage: Mobilize Your Data|website=Design And Reuse}}{{cite web|url=http://www.fonearena.com/blog/242229/ufs-3-0-standard-released-offers-2x-faster-performance-than-ufs-2-1.html|title=UFS 3.0 standard released, offers 2x faster performance than UFS 2.1|website=www.fonearena.com}} and as the physical layer for SuperSpeed InterChip USB.{{cite web|url=https://www.edn.com/electronics-products/electronic-product-releases/audio-design/4375765/MIPI-Alliance-and-USB-3-0-Promoter-Group-Announce-Availability-of-SuperSpeed-USB-Inter-Chip-Specification |title=MIPI Alliance and USB 3.0 Promoter Group Announce Availability of SuperSpeed USB Inter-Chip |publisher=Edn.com |date=2012-06-20 |accessdate=2018-04-22}}{{cite web|url=https://www.iol.unh.edu/testing/mobile/mipi-m-phy|title=MIPI M-Phy Testing Services|date=29 May 2014|publisher=}}{{cite web|url=https://mipi.org/specifications/m-phy|title=MIPI M-PHY|website=mipi.org}}{{cite web|url=https://www.design-reuse.com/articles/25764/mipi-m-phy-ip.html|title=MIPI™ MPHY - An introduction|website=Design And Reuse}}{{cite web|url=https://www.design-reuse.com/articles/23887/mipi-m-phy-ip-core.html|title=MIPI M-PHY takes center stage|website=Design And Reuse}}{{cite web |url=http://eecatalog.com/smartphone/2014/02/27/mipi®-alliance-specifications-drive-4k-and-2k-displays-high-performance-cameras/ |title= Specifications |website=eecatalog.com}}
To support high speed, M-PHY is generally transmitted using differential signaling over impedance controlled traces between components. When use on a single circuit card, the use of electrical termination may be optional. Options to extend its range could include operation over a short flexible flat cable, and M-PHY was designed to support optical media converters allowing extended distance between transmitters and receivers, and reducing concerns with electromagnetic interference.
Applications
M-PHY (like its predecessor{{dubious|reason=M-PHY (v3.1, June 2014); D-PHY (v1.2, September 2014) per MIPI Alliance|date=January 2023}} D-PHY) is intended to be used in high-speed point-to-point communications, for example video Camera Serial Interfaces. The CSI-2 interface was based on D-PHY (or C-PHY), while the newer CSI-3 interface is based on M-PHY. M-PHY was designed to supplant D-PHY in many applications, but this is expected to take a number of years.
The M-PHY the physical layer is also used in a number of different high-speed emergent industry standards, DigRF (High speed radio interface), MIPI LLI (Low latency memory interconnect for multi-processors systems), and one possible physical layer for the UniPro protocol stack.
Signaling speed and gears
M-PHY supports a scalable variety of signaling speeds, ranging from 10 kbit/s to over 11.6 Gbit/s per lane. This is accomplished using two different major signaling/speed modes, a simple low-speed (using PWM) mode and high speed (using 8b10b).{{cite web|url=https://www.youtube.com/watch?v=jXSgmhwrX6s&t=30|title=MIPI M-PHY Electrical Characterisation & Challenges by Parthasarathy Raju, Tektronix - part 1|last=MIPIAlliance|date=18 December 2012|publisher=|via=YouTube}} Communications goes on in bursts, and the design of both high-speed and low-speed forms allows for extended periods of idle communications at low-power, making the design particularly suitable for mobile devices.
Within each signaling method, a number of standard speeds, known as "gears", is defined, with the expectation that additional gears will be defined in future versions of the standard.{{cite web|url=https://www.youtube.com/watch?v=jXSgmhwrX6s&t=336|title=MIPI M-PHY Electrical Characterisation & Challenges by Parthasarathy Raju, Tektronix - part 1|last=MIPIAlliance|date=18 December 2012|publisher=|via=YouTube}}