How to select the right PoC Filter Inductors and Chip Beads for Automotive SerDes (LVDS) Transmission

PoC (Power over Coax) is a transmission system that reduces the number of wires by simultaneously transmitting signals and DC power on a single coaxial cable.
In order to separate the DC power supply from the broadband signals, the system is characterized by the use of a DC-cutting capacitor on the signal line side and a filter inductor on the power supply line to prevent the inflow of broadband signals.
There are a number of communication standards led by IC manufacturers and standardization organizations as shown below, and the appropriate inductor must be selected to match the respective signal transmission speed and power supply.

Sensing devices such as cameras and radar equipment are becoming increasingly high-capacity, high-functionality, and multifunctional as sensing accuracy improves, requiring higher transmission speeds and more power. As a result, PoC filters are required to support higher transmission speeds, from approximately 1.5 Gbps to 10 Gbps or more, and higher supply power, from 1 W to 5 W.

Space is often restricted in automotive camera modules and other products, requiring miniaturization of the product and reduction of the mounting area. A typical filter consists of 2 to 4 inductors together with chip beads, but constraints can often limit the number of products on the mount. In order to reduce the number of inductors, a product that can maintain hight impedance characteristics over a wide bandwidth is required. At the same time, this device must maintain its characteristics in high-temperature environments and operate at temperatures up to 150deg.C.

Under the same conditions as the general PoC filter configuration example above, TDK's inductors for PoC filters can be realized with one inductor. This approach reduces Rdc by 30% and the mounting area by 35%.

As shown in the diagram (Figure 7) below, TDK offers a wide range of inductors for PoC filters that meet your usage conditions, such as allowable current and filter requirements.(See figure 7 below: Solution Map) The MLJ1608-G series, which is compact and covers a high frequency bandwidth, contributes to a space saving filter design. The ADL series is a product that supports a wide bandwidth, and reduces the overall number of filter coils. As a one-coil solution covering a wider bandwidth, there are the ADL3225V, ADL32VHC and ADL8030VA series. Additionally, for high current applications, there are the ADL4532VK series and the ADL3225VF series.

TDK inductors for PoC (Power over Coax) filter circuits

With the increasing speed and sophistication of in-vehicle interfaces, PoC is being promoted in camera systems with SerDes transmission, etc. To separate broadband signals and power in PoC, a wide-band and high-impedance filter using an inductor is required. TDK has a diverse product line-up and can propose filter configurations to suit the current capacity and communication speed of the circuits used.

The above PoC filter combinations are examples of TDK products that are used as references by IC manufacturers or filter combinations recommended by TDK. For choosing the best PoC filter combination under other conditions, use the TDK PoC Selection Tool.

In addition to filters that have already been approved by IC suppliers, we will provide a list of TDK-recommended filters along with samples.
If you are interested, please review the contents of the sample book below and contact us via the contact form.
　Please note: The sample book is available in limited quantities and cannot be sent to individual customers. After submitting the form, we will confirm the intended use and usage conditions. Thank you for your understanding.