A Low Cost Discrete Digital Isolator Circuit
This provides a cost-effective and vendor-independent solution for digital isolation in applications like gate drivers, though it is incremental in its use of existing components.
The paper tackled the problem of creating a low-cost digital isolator without specialized ICs by designing a fully discrete circuit using general-purpose transistors and an air core transformer, achieving >1 kV isolation, ~200 ns propagation delay, and 1 Mbps data rates.
This work presents a fully discrete, low cost digital isolator requiring no specialized ICs and implemented entirely with general purpose transistors and a two layer PCB embedded air core transformer. The design avoids vendor lock in and long term component obsolescence risks, while providing >1 kV isolation, ~200 ns propagation delay, and validated NRZ data rates of 1 Mbps. A modified dual oscillator architecture enables inherent hardware lockout suitable for half bridge gate driver applications. Measured performance and PCB layout guidelines are provided.