When tackling EMI, thorough analysis is imperative. In PCB design, EMI management can be approached from several angles.
1. Device Selection:
In EMI design, the foremost consideration is the speed of the chosen device. Within the circuit, substituting a device with a 5ns rise time for one with a 2.5ns rise time can amplify EMI by approximately fourfold. The intensity of EMI radiation correlates directly with the square of the frequency. The highest EMI frequency, also termed the EMI emission bandwidth, is contingent upon the signal’s rise time rather than its frequency. This radiated EMI typically spans from 30MHz to several GHz. Within this frequency range, wavelengths are notably short, rendering even minimal circuit board wiring susceptible to becoming a transmission antenna. Heightened EMI levels can disrupt the circuit’s normal functioning. Therefore, in device selection, priority should be given to low-speed chips, while still meeting circuit performance requirements. Additionally, employing appropriate driving/receiving circuitry is advisable.
1. Device Selection:
In EMI design, the foremost consideration is the speed of the chosen device. Within the circuit, substituting a device with a 5ns rise time for one with a 2.5ns rise time can amplify EMI by approximately fourfold. The intensity of EMI radiation correlates directly with the square of the frequency. The highest EMI frequency, also termed the EMI emission bandwidth, is contingent upon the signal’s rise time rather than its frequency. This radiated EMI typically spans from 30MHz to several GHz. Within this frequency range, wavelengths are notably short, rendering even minimal circuit board wiring susceptible to becoming a transmission antenna. Heightened EMI levels can disrupt the circuit’s normal functioning. Therefore, in device selection, priority should be given to low-speed chips, while still meeting circuit performance requirements. Additionally, employing appropriate driving/receiving circuitry is advisable.
