Modern Trends in I/O and ESD Design at TSMC OIP

It was very clear at the recent 2025 TSMC OIP Ecosystem Forum that the semiconductor I/O landscape has undergone a profound transformation over the past 25 years, evolving from simple general-purpose input/output (GPIO) cells in 180nm nodes to highly complex, multi-protocol, feature-rich libraries in advanced 16nm and 22nm processes. As Stephen Fairbanks, CEO of Certus Semiconductor, outlines in his presentation, modern I/O design is no longer about basic functionality—it is about adaptability, optimization, and market-specific performance.

Historically, a single foundation I/O library per process node sufficed, offering variants of classic GPIO (push-pull LVCMOS) or open-drain I/O (ODIO) for protocols like I2C or SMBus. These were adequate for early 2000s applications in telecom and consumer electronics. Today, explosive growth in mobile computing, IoT, AI at the edge, automotive infotainment, and autonomous systems demands far greater flexibility. A single ASIC may now serve both automotive (requiring CAN) and cellular (needing I3C) markets without dedicated pins. This convergence has birthed the GPODIO, a hybrid I/O capable of operating in both CMOS and open-drain modes, supporting LVCMOS, SPI, I3C, JTAG, and fail-safe open-drain standards.

The GPODIO exemplifies multi-protocol I/O, a cornerstone of modern design. It features configurable output drivers that switch between high-speed GPIO (Tfall < 5ns, Zout 33–120 Ω) and slow-slew open-drain modes (Tfall 20–1000ns, IOL 3–20mA). Input mode control (IMC) supports multiple VIH/VIL/hysteresis thresholds, while fail-safe operation ensures reliability even with push-pull drivers and on-die terminations. Voltage support has also expanded: modern GPIOs handle VDDIO from 1.2V to 3.3V, core supplies down to 0.65V, and external ODIO voltages up to 5V—all in one cell.

Even more advanced are “Super” I/Os, macro cells combining two single-ended or one differential pair, supporting over 20 standards including LVDS, MIPI, HSTL/SSTL with on-die termination (ODT), and POD. These are essential for high-performance computing (HPC) and 5G infrastructure.

Another major trend is I/O library variants. A single GPIO design in 22nm might spawn five libraries—PM22 (ultra-low power IoT, 0.14nA leakage), MM22 (balanced mobile), OG22 (automotive-grade, 8kV HBM), and EG22/TG22 (HPC with staggered footprints for density). Each optimizes speed, leakage, ESD (2kV to 16kV HBM, 6A to 16A CDM), and interface support (SPI, RGMII, eMMC). Foundry catalogs now offer multiple libraries per node, differentiated by metal stack, voltage, and market focus. Product architects must align library selection with application goals—using a low-power IoT library for HPC would compromise performance.

Analog and RF I/O have also matured. Where once designers built custom pads, modern libraries include pre-characterized cells: low-capacitance RF pads (<75fF, >8kV HBM), matched LVDS/HDMI pairs, and high-voltage analog I/Os up to 20V. This reduces design risk and time-to-market.

Emerging die-to-die interfaces for 2.5D/3D packaging and chiplets introduce ultra-low-power, high-density I/Os (e.g., 4Gbps in 16nm, <0.1nA DC, 10×20µm footprint), critical for multi-die AI and memory stacks.

Verification complexity has skyrocketed. A classic GPIO required ~135 PVT corners; a modern multi-voltage, multi-mode GPODIO demands over 12,000 corners, including zero-volt and power-down modes. Accurate .LIB modeling is now a major engineering challenge.

Bottom line: I/O design has shifted from monolithic, one-size-fits-all libraries to a sophisticated ecosystem of optimized, configurable, and market-tailored solutions. The days of defaulting to the “base” foundry library are gone. Success in 2025 requires deep understanding of application requirements, careful library selection, and robust verification—ensuring performance, power, reliability, and cost align with diverse, demanding end markets.

Certus Semiconductor, with over 30 process node I/O libraries and expertise in ESD, RF, and multi-protocol design, stands at the forefront of this evolution.

Contact Certus for more information

Also Read:

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The 2024 Design Automation Conference and Certus Semiconductor

2024 Outlook with Stephen Fairbanks of Certus Semiconductor