The circuit design of magnetic isolated signal transmission can not take into account simplicity and fastness at the same time. Aiming at this shortcoming and based on to the basic principle of signal modulation and demodulation

a high-speed modulation and demodulation circuit based on emitter coupling is designed. The working principles and the analysis of parameters design are conducted. The experimental results show that when using the transformer of high coupling coefficient

the signal transmission delay is reduced by 25 % compared with other schemes

and the signal transmission delay still guarantees the transmission delay within 50ns when the coupling coefficient changes.