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MIPI Alliance adds physical layer specifications for mobile applications


The MIPI Alliance, an international organization that develops interface specifications for mobile and mobile-influenced industries, introduced its new MIPI C-PHY specification, a physical layer interface for camera and display applications. The specification expands the MIPI Alliance’s family of physical layer specifications, broadening the variety of interface choices available to manufacturers and opening up new opportunities for companies to differentiate their product designs based on business-specific strategies or technology requirements.

“We are very pleased to add MIPI C-PHY to our widely adopted family of physical layer technologies,” says Joel Huloux, chairman of the board of MIPI Alliance. “The MIPI Alliance is all about helping companies interconnect components to create successful mobile designs and as an organization we provide a selection of physical layer technologies to support a full range of application requirements. Companies developing new products can now select from MIPI C-PHY as well as our newly updated MIPI D-PHY specification and MIPI M-PHY specification and apply the specifications to best meet their needs.”

MIPI C-PHY, released as v1.0, is designed to connect camera and display modules to an application processor. The interface allows system designers to easily scale the existing MIPI Alliance Camera Serial Interface (CSI-2) and Display Interface (MIPI DSI) ecosystems to support higher resolution image sensors and displays while at the same time keeping power consumption low. It also supports soft configurability of lanes within a link to optimize bandwidth and minimize pin count. MIPI C-PHY can be implemented with MIPI D-PHY on the same device pins, which allows connections to the companion device with either PHY technology.

“The MIPI C-PHY specification was developed to reduce the interface signaling rate to enable a wide range of high-performance and cost-optimized applications, such as very low-cost, low-resolution image sensors; sensors offering up to 60 megapixels; and even 4K display panels,” said Rick Wietfeldt, chair of the MIPI Alliance Technical Steering Group.

MIPI C-PHY accomplishes this by departing from the conventional differential signaling technique on two-wire lanes and introducing 3-phase symbol encoding of about 2.28 bits per symbol to transmit data symbols on 3-wire lanes, or “trios” where each trio includes an embedded clock. Three trios operating at the MIPI C-PHY v1.0 rate of 2.5 Gsym/s achieve a peak bandwidth of 2.5 Gsym/s times 2.28 bits/symbol, or about 17.1 Gbps over a 9-wire interface that can be shared, if desired, with the MIPI D-PHY interface.

The MIPI Alliance is also pleased to announce the continued development, support and forward progress of its PHY family with updates to the MIPI D-PHY and MIPI M-PHY physical layer technologies. The updated MIPI D-PHY specification, v1.2, introduces lane-based data skew control in the receiver to achieve a peak transmission rate of 2.5 Gbps/lane or 10 Gbps over 4 lanes, compared to the v1.1 peak transmission rate of 1.5 Gbps/lane or 6 Gbps over 4 lanes. The MIPI M-PHY v3.1 specification introduces transmitter equalization to improve support for challenging channels while maintaining the peak transmission rate of 5.8 Gbps/lane or 23.2 Gbps over 4 lanes, which was achieved in its v3.0 specification.

“The MIPI Alliance’s three physical layers, combined with MIPI Alliance application protocols, address the evolving interface needs of the entire mobile device. Fundamentally, MIPI Alliance interfaces enable manufacturers to simplify the design process, reduce costs, create economies of scale and shorten time-to-market,” said Ken Drottar, chair of the MIPI Alliance PHY Working Group.