Friends in “Vehicle Technology” should know that the CAN bus requires two 120 Ohm termination resistors at both ends, making the total line resistance 60 Ohms. This is a piece of knowledge that almost everyone knows, but very few can explain clearly. In most cases, we have the experience that adding a 120 Ohm resistor … Read more
In modern high-frequency microwave circuit design, vertical interconnect transition structures serve as critical paths for signal transmission between different layers of PCBs, and their performance directly affects the overall properties of the system. As communication systems advance into the millimeter-wave frequency band, traditional via structures can no longer meet the integrity requirements for high-frequency signals. … Read more
In modern electronic systems, the design of Radio Frequency (RF) circuit boards has become increasingly complex and critical. With the rapid development of communication technologies, from 5G mobile communications to satellite communications and radar systems, the performance of RF circuits directly affects the quality and reliability of the entire system. The design of RF circuit … Read more
When testing a signal with an output impedance of 50Ω using a Pico oscilloscope, a 50Ω to 1MΩ direct terminal is required. Recently, during an on-site test with a client, I found that the waveform oscillated severely, as shown in Figure 1 (red box), making it impossible to conduct accurate data analysis. Figure 1 Severe … Read more
Click the blue text above to follow us The main reason for adding a 22Ω or 33Ω resistor in series when a microcontroller uses SPI to connect to a sensor or controller is to suppress reflections and ringing. 1 Principle of Reflection and Source Matching In high-speed digital signal transmission, when the signal driver (such … Read more
For more experience sharing, follow RF Engineer When a microcontroller or FPGA sends SPI control signals to a phase-locked loop chip, it often requires a series connection of a 22 ohm or 33 ohm resistor. What is the reason for this? Impedance discontinuities can cause electromagnetic wave reflections, which in turn lead to signal distortion. … Read more