Why is analog circuit design still important in the digital age?

Even in the digital age, analog circuit design plays an important role in converting analog signals, such as human hand gestures and voice, into digital signals. Analog technology is essential for accurate command input and efficient power consumption.

 

In recent years, the terms electronic and digital 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 or 1s. However, by the mid-90s, digital electronics began to be developed one after another, and by the 2000s, analog electronics gradually disappeared as they lost their competitive edge to digital products. As a result, there is no longer any need to distinguish between analog electronics and digital electronics, and the terms digital and electronic have become synonymous. Given this situation, most people might wonder why analog circuit design is becoming increasingly important in a world of digital electronics, but in fact, analog circuit design is one of the most important issues in recent electronic product development. How can analog skills be important in the digital age?
It seems like a paradox, but it’s surprisingly simple to understand when you think about one of the electronics we use most often: our cell phones. Let’s start by looking at why we need analog technology in digital electronics. On a modern cell phone, there are two ways to enter a phone number. If your phone has a touchscreen, you can tap the keypad on the screen, or if your phone has key buttons, you can press the corresponding keys to enter the number. However, since our phones are digital electronics, our hand gestures, such as pressing a button or touching the screen, need to be converted into a signal of 0s and 1s to be interpreted. Therefore, we need a function that converts our hand gestures into 0s and 1s, and analog processing is used to implement this function. Analog processing technology is suitable for receiving inputs such as voice, video, etc. in addition to hand gestures because it deals with continuously changing values. Therefore, even digital electronic products receive inputs from people with the help of analog technology.
So why is analog processing technology becoming increasingly important? Let’s say you’re using a cell phone with a touchscreen, and you press the call button and try to enter your phone number on the screen, but it’s very inconvenient if you press 1 and it thinks you’ve pressed 3, or if your phone doesn’t respond no matter how many times you press it. With the increasing use of touchscreens and voice recognition, which are direct interfaces between humans and electronics, analog technologies that can accurately convert the commands we want to enter into digital signals without error are also needed. In the future, such direct interfaces between humans and digital devices are expected to be used more and more, so analog processing technologies are becoming increasingly important.
How are these analog processing techniques implemented in electronics? If you’ve ever disassembled or repaired an electronic product, you’ve probably noticed the intricate connections of chips of various sizes and shapes on a circuit board. Like many other functions in electronics, analog signal processing is driven by a small number of chips attached to a circuit board, and it’s interesting to look under the hood. Even if the chips have different functions, most of them are made up of only four types of components: resistors, inductors (coils), capacitors, and transistors. Resistors act to interrupt the flow of current, causing a drop in voltage, while inductors interrupt the change in current. Capacitors store charge, and transistors change the current flowing through them based on the input voltage. How these four elements are arranged and connected, with what element values, creates a chip with different functions. Analog circuit design is the study of how resistors, inductors, capacitors, and transistors are arranged to create a chip. Analog circuit design is then used to implement analog processing techniques.
Analog circuit design starts with sizing the transistors for the chip. Often, the size of the transistors is expressed in terms of process size, such as 45 nm, 65 nm, 0.13 um, or 0.18 um. The smaller the process, the more transistors can be integrated, allowing for higher performance circuits. Once the process is determined, the resistors, inductors, capacitors, and transistors are placed according to the purpose of the design. Depending on how they are arranged, the input signal can be amplified or reduced in size, and operations such as addition, subtraction, differentiation, and integration can be performed. Once you’ve designed your circuit, you’ll want to simulate it on a computer to make sure it works, because it’s time-consuming and expensive to build a chip and test it. Simulation often uses a program called SPICE, which calculates what outputs your designed circuit will produce given certain inputs and shows you the results. Once the simulation verifies that the design is correct, it is finally laid out and fabricated into a chip.
In analog circuit design, the main concerns are speed of operation and power consumption. The speed of operation of a chip is determined by its clock number, such as 100 MHz, 800 MHz, or 2.66 GHz, which is commonly found in CPUs and other chips. The number of clocks equals the number of operations per second, so a higher number means faster performance. Increasing the speed of operation results in smaller and less stable output values, so various methods are used to counteract this. On the other hand, as the number of chips in mobile devices increases, there is an ongoing effort to reduce the power consumption of the chip to extend the usage time. This is why power consumption is always a concern in analog circuit design. While smaller process sizes can lead to lower power consumption, they also have the disadvantage of increasing manufacturing costs. Therefore, as new circuit design methods have been researched and applied in recent years, analog circuit design is playing an increasingly important role.
The importance of analog circuit design, which implements analog technology that converts commands from a human user into digital signals so that digital products can recognize the commands, is growing as digital electronics evolve. Until the day comes when we can control our computers with hand gestures like in the movie Minority Report, we can look forward to advances in analog circuit design that will allow us to communicate with our digital products.