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Disruptive Electrical Engineering Technologies: the System-on-Chip

January 10, 2020 by Sam Holland

Almost every kind of electronic device used today utilises a system-on-chip (SoC). Measuring about the size of a human thumbnail, these chips comprise both software and hardware components that add functionality to electronic devices and equipment.

What is a System-on-Chip?

A system-on-chip is an integrated circuit (IC) that combines several electronic components, peripherals, software, and hardware features on a single chip. SoCs can handle many types of signals, including digital, analogue, and mixed signals. In contrast, multi-chip systems consist of several ICs—each contributing a specific function (e.g., signal processing, input/output, memory storage, etc.) to the overall system.


Raspberry Pi as an SoC example.

Raspberry Pi’s use system-on-chips as a nearly fully contained microcontroller. Image Credit: Evan Amos.


A Brief History of the System-on-Chip

The first system-on-chip solution was developed in the 1970s by Willy Crabtree and George Thiess of Electro-Data Incorporated for the world’s first digital watch (aka the Hamilton Pulsar wrist computer). It comprised 44 discrete ICs.

The watch featured a light sensor that gauged the intensity (or lack thereof) of the user’s surrounding ambient lighting and adjusted the brightness of its watch face LED accordingly. This was so that the wearer could always see the time.

The watch was, unsurprisingly, cost-intensive to build, and it sold for $2,100. Two years later, Intel released the Intel 5810 CMOS (complementary metal-oxide-semiconductor) chip in the Micromax watch, which featured a liquid crystal display driver (alongside its timing functions, of course). Today, SoC solutions are utilised in devices that require entire component assemblies to be implemented at the chip level, such as embedded systems, IoT devices, and consumer electronics.


What Are the Components of a System-on-Chip?

SoCs contain all the basic software and hardware requirements of an electronic product. These include:

  • A microprocessor or microcontroller

  • An operating system

  • Input/output ports—such as universal serial bus (USB), serial peripheral interface (SPI), Ethernet, and HDMI ports

  • Internal memory—such as read-only memory (ROM) and random-access memory (RAM)

  • Analogue-to-digital converters (ADCs) and digital-to-analogue converters (DACs).


A diagram of a microcontroller-based system on a chip.

A diagram of the architecture of a microcontroller-based system on a chip, specifically a system-on-chip for ARMImage Credit: Cburnett via Wikipedia.


How Does a System-on-Chip Work?

SoCs contain one or more processor cores that use a reduced instruction set computer (RISC) architecture. Unlike in complex instruction set computers (CISCs), individual cores contain microcontrollers or microprocessors that utilise less digital logic and can perform millions of instructions per second, or MIPS.

Many SoC processor cores utilise Advanced RISC Machine (ARM) architecture, which is cheaper, faster, and more power-efficient than other processor architectures (including Intel’s CPU architecture, the x86).

ARM-based SoCs implement operations via registers, utilise single-cycle execution, as well as maintain only 25 basic instruction types. They also contain digital signal processing (DSP) cores for the execution of signal processing operations for input signals, and these cores usually have application-specific instructions that govern their operations. For storing information, SoCs utilise memories, such as ROM, RAM, and electrically erasable programmable ROM (or EEPROM).

SoCs contain interfaces that support physical communication protocols, such as I²C and the said USB, HDMI, and Ethernet ports, as well as wireless protocols (including the popular Bluetooth, Wi-Fi, and near-field communication (NFC).  They can interface with analogue devices (such as actuators and sensors via ADCs and DACs.


Benefits of System-on-Chip Technology

SoCs offer several benefits over multi-chip solutions for engineers and manufacturers alike. Just some of them are listed below:

  • High reliability and performance: the integrated hardware and software components on such a single chip improve the overall system reliability and performance of electronic devices and equipment, particularly by minimising failure points and optimising on-board connectivity.

  • Low-power operation: SoCs consume less power than multi-chip systems. Modern ICs, such as Qualcomm Snapdragon processors, are designed to maximise power efficiency by using asynchronous symmetric multi-processing (aSMP). This technology allows a chip to power up only the cores that are necessary to perform a particular operation, and it frequently adjusts their frequencies to enable low-power usage.

  • Low profile: as SoCs integrate multiple functions on a single chip, they can be implemented on limited surface areas. Their small footprints make them ideal for use in portable, lightweight products, such as digital cameras, mobile phones, and wearables. 

  • Cost-effectiveness: SoCs are cheaper to design and utilise than multi-chip systems. They are fabricated, due to being manufactured with metal-oxide-semiconductor (MOS) technology, which is low-cost in large production volumes. Due to the fewer number of packages and reduced cabling in SoCs, assembly costs are reduced as well, also resulting in lower costs for end-users.


An apple watch.

System-on-chips are fitted into several low-power electronic devices, such as smartwatches. Pictured: a first-person view of an Apple Watch on its wearer’s wrist. Image Credit: Pixabay.


Limitations of System-on-Chip Technology

Although SoC systems are beneficial to manufacturers across several metrics, they do have the following drawbacks:

  • High initial production costs: the design and development phases of new SoC solutions are cost-intensive. For small production runs, fabrication costs are considerably higher, resulting in higher costs for end users.

  • Costly replacements: any failures of individual units or components within a chip can greatly impact the functions of the assembly and/or result in catastrophic failures. Replacements can be costly.


Modern applications for SoCs are nearly limitless due to their low power consumption, small footprints, high reliability, and increasing computing capabilities. Today, the global SoC market is growing rapidly, largely due to its adoption in robotics, computing, and consumer electronics—plus of course its increased investment for the upcoming 5G standard.

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