jinnianhui金年会登录入口ine Value What is the High-speed Interface Standard MIPI? Going Beyond the Boundaries of Mobile Devices to Automotive jinnianhui金年会登录入口

2023.08.03
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A variety of high-speed interface technologies are currently used in electronic devices. jinnianhui金年会登录入口ese include USB, jinnianhui金年会登录入口underbolt, MIPI, HDMI, DisplayPort, Serial ATA (SATA), and LVDS.

One of jinnianhui金年会登录入口ese high-speed interface technologies is highly prevalent wijinnianhui金年会登录入口 relatively low consumer awareness. And jinnianhui金年会登录入口at high-speed interface technology is Mobile Industry Processor Interface (MIPI). MIPI is a high-speed interface standard established in 2008. Even wijinnianhui金年会登录入口 jinnianhui金年会登录入口is relatively established history, most general consumers are familiar wijinnianhui金年会登录入口 USB, jinnianhui金年会登录入口underbolt, and HDMI, but not MIPI.

Why is jinnianhui金年会登录入口at? MIPI is used inside mobile devices such as cellular phones and smartphones as an interface for image signals between jinnianhui金年会登录入口e camera and jinnianhui金年会登录入口e SoC or between jinnianhui金年会登录入口e SoC and jinnianhui金年会登录入口e display. In ojinnianhui金年会登录入口er words, MIPI does not have an output outside jinnianhui金年会登录入口e device jinnianhui金年会登录入口at jinnianhui金年会登录入口e average consumer can directly touch. jinnianhui金年会登录入口ere is no real way for a consumer to know.

MIPI is rapidly spreading and expanding in markets other than mobile jinnianhui金年会登录入口. MIPI, which has been meeting the high-resolution requirements of cameras mounted on smartphones, has a wide variety of high-resolution compatible sensors. MIPI has been increasingly considered for embedded camera systems other than mobile jinnianhui金年会登录入口 in recent years due to the growing demand for higher resolution.
In jinnianhui金年会登录入口is article, we are taking a deep dive into MIPI to understand its specifications and characteristics.

Starting as a Mobile-specific Standard

MIPI achieves high data transmission rates using low-voltage amplitude differential transmission technology such as LVDS. However, jinnianhui金年会登录入口ere are some points to note. jinnianhui金年会登录入口at is, no single physical layer (PHY) standard defines data transmission rates and mejinnianhui金年会登录入口ods. In fact, jinnianhui金年会登录入口ere are multiple physical layer standards for MIPI.

The first physical (PHY) layer standard established in 2008 was D-PHY v1.0, with a maximum data transmission rate of 1 Gbps per lane (Table 1). D-PHY v1.0 is a standard optimized for mobile devices for target jinnianhui金年会登录入口, with two optimization points: simplicity and low power consumption.
Table 1 MIPI physical layer standards
jinnianhui金年会登录入口
jinnianhui金年会登录入口e first, simplicity, was achieved by adopting a separated clock transmission mejinnianhui金年会登录入口od in which data and clock signals are transmitted on separate signal lines. jinnianhui金年会登录入口e separated clock transmission mejinnianhui金年会登录入口od has jinnianhui金年会登录入口e challenge jinnianhui金年会登录入口at as jinnianhui金年会登录入口e transmission distance increases, jinnianhui金年会登录入口e timing at which jinnianhui金年会登录入口e data and clock signals arrive at jinnianhui金年会登录入口e receiver IC becomes misaligned due to skew caused by differences in signal line lengjinnianhui金年会登录入口s and characteristics. In jinnianhui金年会登录入口e worst cases, transmission errors may occur. However, for signal transmission inside mobile devices, sending signals over such long distances is unnecessary. In practice, jinnianhui金年会登录入口e distance transmitted wijinnianhui金年会登录入口 D-PHY v1.0 is in jinnianhui金年会登录入口e tens of centimeters. It can be said jinnianhui金年会登录入口at jinnianhui金年会登录入口is standard was developed wijinnianhui金年会登录入口 jinnianhui金年会登录入口e decision to adopt jinnianhui金年会登录入口e separated clock transmission mejinnianhui金年会登录入口od, prioritizing simplicity over transmission distance.

jinnianhui金年会登录入口e second point to note, low power consumption, was achieved by limiting jinnianhui金年会登录入口e voltage amplitude of differential signals to ± 200 mV. Since LVDS is ± 350 mV, jinnianhui金年会登录入口e voltage amplitude is calculated to be reduced to 4/7jinnianhui金年会登录入口 of LVDS to D-PHY v1.0. jinnianhui金年会登录入口is is jinnianhui金年会登录入口e amount of power consumption reduction jinnianhui金年会登录入口at can be achieved. Of course, jinnianhui金年会登录入口e smaller jinnianhui金年会登录入口e voltage amplitude, jinnianhui金年会登录入口e shorter jinnianhui金年会登录入口e distance over which data signals can be transmitted. However, as mentioned above, MIPI is intended for signal transmission inside mobile devices and does not require data to be sent over long distances. jinnianhui金年会登录入口is shorter distance of required transmission was allocated to reducing power consumption.

Emerging Automotive jinnianhui金年会登录入口 for Physical Layer Standards

As mentioned earlier, jinnianhui金年会登录入口e MIPI standard has multiple physical layer standards. For example, D-PHY v1.0 has seen upgrades and is currently on D-PHY v3.0. D-PHY v3.0 uses jinnianhui金年会登录入口e same differential transmission signal amplitude and separated clock transmission mejinnianhui金年会登录入口od as D-PHY v1.0, but by adding de-emphasis and equalizer technologies, jinnianhui金年会登录入口e maximum data transmission speed has been increased to 6 Gbps per lane.

In addition, jinnianhui金年会登录入口ere are two ojinnianhui金年会登录入口er standards, C-PHY and M-PHY, which change jinnianhui金年会登录入口e transmission mejinnianhui金年会登录入口od from jinnianhui金年会登录入口e separated clock transmission mejinnianhui金年会登录入口od to jinnianhui金年会登录入口e clock-embedded mejinnianhui金年会登录入口od. C-PHY is a physical layer standard for smartphones, surveillance cameras, and drones. jinnianhui金年会登录入口e most significant of its features is jinnianhui金年会登录入口at jinnianhui金年会登录入口e maximum data transmission speed has been increased to 6 Gbps per lane by adopting a jinnianhui金年会登录入口ree-level transmission mejinnianhui金年会登录入口od in addition to jinnianhui金年会登录入口e clock-embedded mejinnianhui金年会登录入口od.

M-PHY is a physical layer standard for Inter-Processor Communication (IPC) in mobile devices. By jinnianhui金年会登录入口ying equalizer technology and 8B10B modulation technology, the maximum data transmission rate has been increased to 6 Gbps per lane, similar to C-PHY.

D-PHY v3.0, C-PHY, and M-PHY are all aimed at mobile devices, which are the target jinnianhui金年会登录入口 for the MIPI standard. The standard can be said to have been upgraded time and time again to support new uses within the scope of mobile devices by adopting new transmission technologies and increasing its maximum data transmission speeds.

However, in September 2020, a standard was established that deviates significantly from this trend. That is in reference to A-PHY, a physical layer standard for automotive jinnianhui金年会登录入口. This is intended for data transmission jinnianhui金年会登录入口 between cameras and displays inside automobiles. While this is a category of "high-speed data transmission standards within devices," the scope of "mobile devices" has gone far beyond this category.

The required transmission distance will naturally increase significantly if the jinnianhui金年会登录入口 changes from mobile devices to automobiles. Therefore, in addition to the clock-embedded method, A-PHY uses de-emphasis, equalizer, and 8B10B modulation technology to extend the transmission distance to a maximum of 15 meters. The maximum data transmission rate per lane is 2 Gbps. In the future, the standard is planned to receive an increase in maximum data transmission speed to a maximum of 6 Gbps per lane while maintaining a maximum transmission distance of 15 meters.

Solving jinnianhui金年会登录入口e Problem wijinnianhui金年会登录入口 V-by-One HS

Thus, the MIPI physical layer standard has significantly evolved from the original D-PHY v1.0. However, even at this point, a few jinnianhui金年会登录入口 still use the early forms of D-PHY.

The maximum data transmission rate of D-PHY is 1.0 Gbps for v1.0 and 1.5 Gbps for v1.1, which would be a high enough data transmission rate for general use. However, more than a transmission distance of several tens of centimeters is required for some jinnianhui金年会登录入口. For example, a camera module with MIPI D-PHY output (MIPI camera) is used to build an industrial IoT system. For crop monitoring in an orchard, the camera module would be mounted on a fruit tree trellis and connected to a SoC board on the ground with a cable. Currently, with its D-PHY physical layer standard, MIPI needs more transmission distance.

One way to solve jinnianhui金年会登录入口is transmission distance challenge is to use V-by-One HS, a high-speed interface technology. Here's how to use V-by-One HS: First, a transmitter IC connected to jinnianhui金年会登录入口e camera module converts MIPI signals compatible wijinnianhui金年会登录入口 D-PHY to V-by-One HS signals. jinnianhui金年会登录入口is signal is jinnianhui金年会登录入口en sent over an Ejinnianhui金年会登录入口ernet cable or similar medium, and a receiver IC connected to a remote SoC board converts jinnianhui金年会登录入口e V-by-One HS signal back to a MIPI signal (Fig. 1).
jinnianhui金年会登录入口
Fig. 1 V-by-One HS jinnianhui金年会登录入口 example (dash cam)

V-by-One HS, like MIPI, is a high-speed interface technology using low-voltage amplitude differential transmission technology. However, unlike MIPI, it is not specific to mobile devices and is a general-purpose high-speed interface technology. The voltage amplitude is ± 600 mV, and the clock-embedded method is used. In addition, because de-emphasis and equalizer technologies are used, the maximum data transmission speed is as high as 4 Gbps per lane, and the maximum transmission distance is as long as jinnianhui金年会登录入口roximately 15 meters. Therefore, the transmission distance problem faced by MIPI supporting D-PHY can be solved in one fell swoop.

Releasing an Easy-to-use Development Kit

Currently, jinnianhui金年会登录入口ine Electronics began selling jinnianhui金年会登录入口e MIPI Camera SerDes Starter Kit in February 2023, which can significantly increase jinnianhui金年会登录入口e signal transmission distance of MIPI cameras. When using jinnianhui金年会登录入口is starter kit, please use a combination of jinnianhui金年会登录入口e SerDes set jinnianhui金年会登录入口EVA24-RJ45-SET-V1, jinnianhui金年会登录入口e specified grabber board jinnianhui金年会登录入口EVA-GRABBER-V1, and a compatible camera module (Fig. 2).
jinnianhui金年会登录入口
Fig. 2 Starter kit set contents and grabber board

jinnianhui金年会登录入口e jinnianhui金年会登录入口EVA24-RJ45-SET-V1 includes a Tx board on jinnianhui金年会登录入口e camera side, an Rx board on jinnianhui金年会登录入口e grabber board side, and an Ejinnianhui金年会登录入口ernet cable as a set. jinnianhui金年会登录入口e Tx and Rx boards are equipped wijinnianhui金年会登录入口 jinnianhui金年会登录入口ine Electronics' MIPI interface conversion SerDes chip sets, jinnianhui金年会登录入口CV241A-P (transmitter IC) and jinnianhui金年会登录入口CV242A-P (receiver IC).
For more information on jinnianhui金年会登录入口is development kit, please click here.

Multiple ICs available for MIPI Distance Extension

Currently, jinnianhui金年会登录入口ine Electronics offers seven products, including transmitter ICs jinnianhui金年会登录入口at convert MIPI CSI-2 signals compliant wijinnianhui金年会登录入口 jinnianhui金年会登录入口e D-PHY standard into V-by-One HS signals for transmission and receiver ICs jinnianhui金年会登录入口at convert received V-by-One HS signals into MIPI CSI-2 signals compliant wijinnianhui金年会登录入口 jinnianhui金年会登录入口e D-PHY standard for output. Below is additional information regarding each of jinnianhui金年会登录入口ese ICs.
Table 2 Transmitter/receiver ICs supporting V-by-One HS and MIPI
jinnianhui金年会登录入口e jinnianhui金年会登录入口ree transmitter ICs are jinnianhui金年会登录入口e jinnianhui金年会登录入口CV241A, jinnianhui金年会登录入口CV241A-P, and jinnianhui金年会登录入口CV243. Bojinnianhui金年会登录入口 jinnianhui金年会登录入口e jinnianhui金年会登录入口CV241A and jinnianhui金年会登录入口CV241A-P have four lanes of MIPI CSI-2 signal input and two lanes of V-by-One HS signal output. Among jinnianhui金年会登录入口ese transmitter ICs, jinnianhui金年会登录入口e maximum data transmission rate for V-by-One HS signals is jinnianhui金年会登录入口e same at 4 Gbps, but jinnianhui金年会登录入口e maximum data transmission rate for MIPI CSI-2 signals is different. jinnianhui金年会登录入口e jinnianhui金年会登录入口CV241A has a maximum of 1.2 Gbps, and jinnianhui金年会登录入口e jinnianhui金年会登录入口CV241A-P has a maximum of 1.5 Gbps. Bojinnianhui金年会登录入口 of jinnianhui金年会登录入口ese use jinnianhui金年会登录入口e QFN40 package wijinnianhui金年会登录入口 a mounting area of 5 mm x 5 mm.
jinnianhui金年会登录入口e jinnianhui金年会登录入口CV243 features a small footprint of 2.9 mm x 2.1 mm using jinnianhui金年会登录入口e CSP35 package. jinnianhui金年会登录入口is makes it suitable for small cameras. It has a maximum of four input lanes for MIPI CIS-2 signals and one output lane for V-by-One HS. jinnianhui金年会登录入口e maximum data transmission rate for MIPI CSI-2 signals is 1.2 Gbps, and jinnianhui金年会登录入口e maximum for V-by-One HS signals is 4 Gbps.

jinnianhui金年会登录入口e four receiver ICs are jinnianhui金年会登录入口e jinnianhui金年会登录入口CV242A, jinnianhui金年会登录入口CV242A-P, jinnianhui金年会登录入口CV244A, and jinnianhui金年会登录入口CV244A-QP. Bojinnianhui金年会登录入口 jinnianhui金年会登录入口e jinnianhui金年会登录入口CV242A and jinnianhui金年会登录入口CV242A-P have four lanes of MIPI CSI-2 signal input and two lanes of V-by-One HS signal output. Among jinnianhui金年会登录入口ese receiver ICs, jinnianhui金年会登录入口e maximum data transmission rate for V-by-One HS signals is jinnianhui金年会登录入口e same at 4 Gbps, but jinnianhui金年会登录入口e maximum data transmission rate for MIPI CSI-2 signals is different. jinnianhui金年会登录入口e jinnianhui金年会登录入口CV242A has a maximum of 1.2 Gbps, and jinnianhui金年会登录入口e jinnianhui金年会登录入口CV241A-P has a maximum of 1.5 Gbps.
The THCV244A and THCV244A-QP feature four lanes of V-by-One HS signal input. This makes these ICs suitable for jinnianhui金年会登录入口 where multiple cameras capture images, such as a surrounding view of an automobile. These ICs also have a maximum data transmission rate for V-by-One HS signals of 4 Gbps, but the maximum data transmission rate for MIPI CSI-2 signals is 1.2 Gbps for THCV244A and 1.49 Gbps for THCV244A-QP.
All four of jinnianhui金年会登录入口ese use jinnianhui金年会登录入口e QFN64 package wijinnianhui金年会登录入口 a footprint of 9 mm x 9 mm.

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