Custom Integrated Circuit Design: Exploring FPGA and Semi-Custom Solutions

Have you ever wondered if it's possible to send in a logic gate diagram or a normal circuit diagram and receive an integrated circuit (IC) chip that performs your custom function? This article explores the history and current state of semi-custom IC production, as well as the modern alternative using field-programmable gate arrays (FPGAs).

From Past to Present: Semi-Custom ICs

In the past, there was a service known as semi-custom ICs, where customers could provide a schematic of pre-designed function blocks, such as basic logic gates and analog components like operational amplifiers (opamps), and have an IC produced with them connected as needed. These function blocks were then encapsulated within the IC and completed with a metalization layer to create a finished product ready for packaging. Although this service has become less common, its concepts are still relevant today.

Modern Alternatives: FPGAs

Today, the closest equivalent to the semi-custom IC service is the use of Field Programmable Gate Arrays (FPGAs). An FPGA is a type of integrated circuit whose logic and interconnect can be programmed by the user. These devices are highly programmable and can serve as a flexible hardware platform. While they are initially intended for development and prototyping, they can be adapted for final products, making them an attractive option for custom circuits.

Why Not Direct Custom IC Production?

Direct production of custom IC chips from logic gate diagrams or circuit schematics is not feasible due to the extensive process required in semiconductor production. Instead, modern solutions like FPGAs and system level programming offer a more practical approach.

Using FPGAs for Custom Circuits

FPGAs are often recommended for custom circuit design due to their flexibility. These devices are used by both big semiconductor companies and developers for final product projects. The advantage is that they guarantee a higher first-pass success rate, ensuring that the design works reliably from the first attempt. Additionally, there are Silicon compilers available that support the transition from C language to VHDL for programming FPGAs. These compilers also provide direct interfaces to the technology and manufacturing processes. This means you can even integrate the development of the chip's external software and firmware while simultaneously designing the chip itself.

With these tools, you can test the initial samples of a video processor or similar device soon after the first batch of packaged chips is produced. For example, a working video display can be achieved in a matter of hours after the chips are packaged and tested in the lab. An IR control for picture parameters can also be operational within the same timeframe.

Silicon Compiler and Production End

The production side of these Silicon compilers is provided by the selected producer of the chip. The compiler will include the necessary process-related parts to produce the final chip, or the producer can do this based on the VHDL model. If the idea shows promise, it may be feasible to discuss a shared wafer lot, where chips are processed along with other experimental or low-volume projects.

Financial Considerations for High-Turnover Projects

For projects with high turnover, discussing a shared wafer lot can be a viable option. While it may not be cost-effective for all projects, it is feasible when financially backed. The key is to be prepared for the extra work in the processing and special handling required for such projects.