Low-Delay High-CMTI Digital Isolator Based on Set-Reset Modulation Technique Used in IGBT Drivers

Digital isolators have been widely used in IGBT drivers to achieve electrical isolation between different systems. Due to the harsh operating environment of IGBTs, electromagnetic interference can easily cause output errors in isolators, leading to system failures. In this paper, a low-delay and high-immunity digital isolator based on set/reset modulation technique is proposed. It employs two sets of on-chip transformers to transmit set and reset signals with refreshing information. This approach ensures low delay while significantly improving the immunity of the signal transmission link against interference. The proposed digital isolator is designed based on the SMIC 0.18um BCD process. According to the simulation results, the turn-on transmission delay of the digital isolator is 5.66ns, the turn-off transmission delay is 5.79ns, the pulse width distortion is 0.13ns, and the common mode transient immunity (CMTI) reaches 200kV/us.