A Study on Supply Voltage Control for VOH Drift Reduction in TSV I/O Interfaces

In this paper, various NN driver architectures are compared and analyzed to address the VOH-drift problem occurring in TSV (Through-Silicon Via)-based HBM (High Bandwidth Memory) interfaces. To mitigate the slew rate degradation and power increase caused by the large parasitic capacitance of TSVs, three structures are compared: conventional NN driver, NN driver with a leaker NMOS, and the NN driver with a VOH drift controlled pre-driver. Simulation results show that the conventional NN driver exhibits significant VOH-drift, while the leaker NMOS structure can eliminate the drift but causes a considerable increase in static power consumption. The VOH drift controlled pre-driver improves power efficiency. However, it introduces an undershoot phenomenon. Moreover, reducing the main driver voltage effectively suppresses VOH drift, but a trade-off relationship exists in which the drift increases as the pre-driver voltage decreases. This study provides a design direction for simultaneously improving power efficiency and signal integrity in HBM interfaces.