Understanding Integrated Circuit Technology: Types, Trends, and Moore's Law

The lecture begins with an introduction to integrated circuit (IC) technology, emphasizing that every processor must ultimately be implemented on an IC, commonly referred to as a chip. IC technology involves mapping a digital gate-level implementation onto a semiconductor device, which consists of interconnected transistors and other components.

The discussion highlights that various processes exist for building semiconductors, with complementary metal-oxide-semiconductor (CMOS) technology being the most popular. It is noted that IC technology is independent of processor technology, meaning any processor can be mapped to any IC technology.

To understand the differences among IC technologies, the speaker explains that semiconductors consist of multiple layers: the bottom layers form transistors, the middle layers create logic components, and the top layers connect these components with wiring. The process of creating these layers involves depositing photosensitive chemicals on the chip surface and using light to alter the chemical properties, which requires designing appropriate masks, often referred to as layouts.

The speaker mentions that the narrowest line that can be created on a chip is termed the feature size, which is currently below 1 micrometer, indicating advancements in IC technology. Each layer must be constructed to produce a functional IC, prompting the audience to consider who and where these layers are built.

In discussing full custom IC technology, the speaker explains that all layers are optimized for specific embedded system designs. This optimization includes strategically placing transistors to minimize interconnection lengths, sizing transistors for optimal signal transmission, and routing wires among transistors. Once the masks are completed, they are sent to a fabrication plant for actual IC production. Full custom IC design, also known as very large scale integration (VLSI) design, is characterized by high non-recurring engineering (NRE) costs and long turnaround times, often taking several months before the ICs are available.

The lecture transitions to semi-custom application-specific integrated circuits (ASICs), which include gate array and standard cell technologies. In gate array ASIC technology, the lower layers are either fully or partially constructed, allowing designers to focus on completing the upper layers. The existing IC consists of an array of gates, and the primary task is to connect these gates for specific implementations. In standard cell ASIC technology, logic cells are utilized to achieve the desired functionality.

The discussion begins with the explanation of ASICs (Application-Specific Integrated Circuits), which are the most popular IC technology due to their good performance and size, coupled with significantly lower non-recurring engineering (NRE) costs compared to full custom ICs. However, the manufacturing process for AI ASICs can still take weeks or even months.

Next, the speaker introduces Programmable Logic Devices (PLDs), highlighting that all layers of these devices already exist, allowing for the purchase of the actual IC before finalizing the design. The programming of PLDs involves creating or destroying connections between wires that connect gates, typically performed by small devices called programmers connected to desktop computers. PLDs are categorized into simple and complex types, with examples including Programmable Logic Arrays (PLAs) and Programmable Array Logic (PALs).

The speaker notes the rapid growth in popularity of Field Programmable Gate Arrays (FPGAs) over the past decade. FPGAs provide more general connectivity among logic blocks compared to PLAs and PALs, enabling the implementation of more complex designs. Despite their larger size, higher unit costs, and potentially greater power consumption, FPGAs are well-suited for rapid prototyping due to their low NRE costs and instant IC availability.

The conversation shifts to trends in embedded systems, particularly focusing on Moore's Law, which states that the capacity of IC transistors has doubled approximately every 18 months for several decades. This exponential increase in logic transistors per chip is evident in daily life, with the speaker illustrating the significant reduction in transistor size from 10,000 in 1981 to about 15 crore in 2002, showcasing the advancements in technology.

The speaker concludes the discussion by encouraging viewers to engage with the content, asking them to like the video if they found it helpful and to subscribe to the channel if they are new, expressing gratitude for their viewership.