Why is analog circuit design still essential in an era dominated by digital technology? The ability to process continuous analog signals, such as voice, touch, and environmental data, and digitize them enables us to communicate with the real world. In particular, autonomous driving, smartphones, and medical devices require precise data processing that combines digital and analog signals.
In recent years, the terms electronic and digital products have become interchangeable. Until the early 90s, the signals used inside electronics were mostly analog, with values that varied continuously over a range, rather than digital, with only 0s and 1s. However, in the mid-90s, digital electronics began to be developed one after another, and in the 2000s, analog electronics gradually disappeared as they lost their competitiveness to digital products. As a result, the distinction between analog and digital electronics became unnecessary, and the terms digital and electronic have been used interchangeably.
However, when we talk about the recent resurgence of analog circuit design, most people might wonder why analog technology is needed now that digital electronics are so commonplace. In fact, analog circuit design has become an integral part of recent electronics development, especially in areas that require dealing with continuous signals in the real world, where digital signal processing alone has limitations. For example, continuous data such as the human voice, touch input, and environmental changes such as temperature and humidity are often difficult to simply convert into digital signals. Processing these data requires analog methods that cannot be completely replaced by digital signals. So why is analog technology so important in the digital age?
Let’s take our everyday cell phones as an example: there are two ways to enter a phone number on your phone. If you have a phone with a touchscreen, you can tap the keypad on the screen, or if you have a phone with key buttons, you can press those keys to enter the number. The various commands we type on our phones, including touch gestures, are converted to 0s and 1s. However, our hand gestures or voice commands are continuously varying analog signals. To convert these signals to digital signals and interpret them, we need analog circuits. Analog circuits become a key technology to help us process these continuous signals with precision.
In addition, many electronic devices today require complex functionality, requiring designs that more closely combine analog and digital circuits. For example, when using a camera on a smartphone, digital signal processing circuits are responsible for storing the image digitally, but analog circuits are used in the initial process of converting light into electrical signals. In this way, many modern electronic devices use a combination of analog and digital technologies.
So why are analog processing skills particularly important? For example, if you’re using a touchscreen, it’s frustrating when the device doesn’t respond exactly as you intend. The more precise the technology becomes in interpreting analog signals and converting them to digital signals, the more naturally the user can command the device. These interfaces allow users to interact more intuitively with their electronics, and analog circuit design is becoming increasingly important.
How are these analog processing techniques implemented inside electronics? When you look inside an electronic product, you’ll see a complex arrangement of chips of various sizes and shapes. These chips are mostly composed of resistors, inductors (coils), capacitors, and transistors. Resistors act to limit current flow to drop the voltage, inductors interfere with current changes, capacitors store charge, and transistors regulate current flow based on voltage. The way these four elements are combined and arranged creates a circuit that performs a specific function, and the process of designing them is called analog circuit design.
One of the key factors in analog circuit design is the speed of operation and power consumption of the chip. In recent years, the clock frequency of high-speed chips, such as CPUs, has become increasingly important, as higher clock frequencies allow more operations to be performed. Along with this, various design approaches are being explored to reduce power consumption. For example, in mobile devices where battery life is critical, power efficiency is becoming more important in analog circuit design. As processes get smaller, i.e., transistors get smaller, power consumption decreases, but at the cost of increased fabrication costs, so there are many trade-offs that need to be made at the design stage.
Systems that take advantage of the best of both digital and analog signals will be increasingly required in the future. For example, signal processing for sensors in self-driving cars or medical devices requires analog circuit design to relay human sensations to the device as accurately as possible. Furthermore, the ability to control devices with hand gestures or eye movements, as seen in movies, requires analog circuit designs that can accurately recognize subtle human movements.
Analog technologies that convert user commands into digital signals and enable digital products to understand them are becoming increasingly important as digital electronics evolve. Advances in analog circuit design will continue to be exciting as it connects digital devices to the real world.
