Integrated-injection logic (I²L): Does I²L offer high device density and simpler fabrication compared to TTL, enabling very compact digital circuits?

Introduction / Context:Integrated-injection logic (I²L), also called merged-transistor logic, was designed for very high packing density with low power, competing historically with TTL and ECL in certain applications. This question checks recognition of I²L’s density and process simplicity advantages.

Given Data / Assumptions:

• I²L uses bipolar transistors with current injection for logic operation.
• Low supply voltage and low power consumption.
• Goal: maximize density and simplify fabrication steps.

Concept / Approach:By merging devices and using lateral pnp injectors feeding multiple npn transistors, I²L attains high logic density with fewer processing steps than TTL (which needs multiple diffusions and complex structures). Although slower than the fastest TTL/ECL, I²L’s benefits are area and power.

Step-by-Step Solution:

Verification / Alternative check:Historic literature and textbooks highlight I²L’s extremely high gate density and simple process, particularly in early low-power VLSI contexts.

Why Other Options Are Wrong:

• “Larger and more complex” contradicts the design goal of I²L.
• “Analog-only” mischaracterizes a digital logic family.
• “Requires >10 V” is incorrect; I²L uses low supply voltages.

Common Pitfalls:Assuming density always correlates with speed; I²L trades off speed for density and simplicity.

Final Answer:Valid — I²L offers high density with simple fabrication compared to TTL.