An Optocoupler Chip Design Based on BiCMOS Technology

An optocoupler chip is proposed in this paper based on BiCMOS process. NPN transistors are utilized as input transistors for transimpedance amplifier (TIA) and comparator to achieve low noise and low offset. Darlington composite transistor and NMOS achieve a class AB output driver circuit. The simulation results show that the optocoupler can work in the supply voltage range of 15$\sim$30V, and the peak output current can reach 2.85A. Meanwhile, with a 10$\Omega$ resistor and a 10nF capacitor in series at output, the measured rise time tr of the output signal is 60ns, the fall time tf is 67.3ns, the rise propagation delay time tPLH is 118ns, and the fall propagation delay time tPHL is 113.8ns.