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Source: Xilinx
Abstract: There are many types of chips, and even industry insiders find it difficult to accurately classify and fully understand them. The public’s understanding of chips can be said to be limited. This article attempts to take a “family portrait” of the chip family to provide a comprehensive understanding of this family. In fact, this attempt is quite challenging. Chips are like the stars in the vast universe; the more carefully you observe, the more you will discover. Countless and chaotic, it is a struggle to understand, and it leaves a unique feeling in the heart…
Integrated circuits (chips) are widely used and come in many varieties with complex models. Whenever a new application demand arises, a new chip is created. To depict the full picture of the chip family, we first need to classify them. There are many classification methods for chips, such as by transistor operating state, manufacturing process, applicability, integration scale, power rating, packaging form, application environment, and functional purpose. Different focuses lead to different classification methods.
This article focuses on the operating states of transistors in chips and types of electrical signals, roughly dividing the chip family into four categories: Digital Circuit chips, Analog Circuit chips, Mixed-signal Circuit chips, and Special Circuit chips.
Figure 1. A simple classification of the chip family
1. Digital Circuit Chips
Digital circuit chips are mainly used in computers and logic control fields. Their working principle is to control the “on” and “off” of current through transistors to express data or information as “1” and “0”, or to express logical judgments as “yes” and “no”. Therefore, digital circuits are also called switching circuits or logic circuits. Digital circuits are primarily composed of transistors operating in a switching state. Hence, the scale of digital circuits is classified by the number of transistors they contain. Digital circuit chips mainly include the following seven categories.
1.Logic Circuits(including AND gates, OR gates, NOT gates, latches, shift registers, counters, encoders, decoders, multiplexers, comparators, arithmetic units, etc.): The internationally recognized series of logic circuit chips include the 74 series, 40 series, 54 series, manufacturer-compatible series, and non-series dedicated circuits. For instance, the 74 series has over 97 functional models, and each model can give rise to more than four times the varieties when considering different input/output numbers, power supplies, power consumption, speed, etc., totaling more than 400 varieties. Just the logic circuit chips alone are already quite complex.
However, regardless of how many types of logic circuits there are, they are fundamentally composed of AND gates, OR gates, and NOT gates. Therefore, the aforementioned series of circuits are also referred to as combinational logic circuits. AND gate circuits are used for judgments where “results only occur if several input conditions exist simultaneously; otherwise, there are no results”; OR gate circuits are used for judgments where “results occur if at least one of several input conditions exists; no results occur if none exist”; NOT gate circuits are used for judgments where “if input conditions exist, there are no results; if input conditions do not exist, there are results”. These judgments and processes can be combined to handle very complex control and computation problems.
Figure 2. Three basic logic chips
Theoretically, a large number of logic circuit chips can implement all complex chip functions, such as central processing units (CPUs), microcontrollers (MCUs), and systems on chips (SoCs). Moreover, they can even implement the functions of a complex system, such as computers and switches. However, thousands, or even more chips would need to be installed on the printed circuit board (PCB). Early electronic products were designed this way, but today it is no longer necessary. Because modern chips have high integration levels, many self-contained logic circuits can be integrated within a chip, allowing a single chip to achieve very complex functions, such as a CPU, or even implement a complete system, such as an SoC. Therefore, today, no one is willing to use a large number of small chips to create a large system, as that would result in large, unreliable, and costly systems.
Figure 3. Examples of some combinational logic circuit chips
Today, the usage of logic circuit chips is not very high. Just like building a house, you can either use bricks and tiles entirely or use some large components supplemented by a small amount of bricks and tiles, naturally reducing the amount of bricks and tiles used. Nowadays, logic circuit chips are mainly used in small electronic products or in the connection circuits between large general-purpose chips in large systems.
2.General-purpose Processors(CPUs, GPUs, DSPs, APU, etc.): General-purpose processors are composed of a massive number of logic circuits, including control, storage, computation, input/output, etc., forming a complete data and information processing system. They are the largest and most complex category of digital circuit chips. (Based on the integration of over 10 billion transistors on a general-purpose processor chip, it roughly contains over 3 billion AND gates, OR gates, and NOT gates.) Thus, general-purpose processors are classified as large-scale integrated circuits.
General-purpose processor chips are characterized by continuous iteration according to Moore’s Law, resulting in the emergence of several product series. For example, Intel and AMD’s x86 series, IBM’s PowerPC series, MIPS’s embedded CPU series, and ARM RISC series, among many others. Each series has produced 20 to 30 chip models, and each model has an average market lifespan of about 2 years.
Figure 4. Examples of some general-purpose processor chips
General-purpose processors are known as the brain and core of electronic products and information systems. The central processing unit (CPU) is used to manage, schedule, and control the coordinated and efficient operation of all components of electronic products and information systems; the graphics processing unit (GPU) receives management from the CPU but can independently manage, schedule, and control tasks related to image display and graphics processing; the digital signal processor (DSP) also accepts management from the CPU but can independently complete a large number of rapid computations and processing of data and information; with the rapid development of artificial intelligence technology, the traditional CPU structure cannot meet the requirements of AI systems for information storage, computation, and reasoning, leading to the emergence of innovative new processor structures, flourishing in variety. This is represented by artificial intelligence processors (APUs), with representative products like IBM’s TrueNorth, Qualcomm’s Zeroth, Google’s TPU, Microsoft’s Brainwave, Cambricon’s Cambricon-1A, and Suiyuan Technology’s DTU.
3.Memory(SRAM, DRAM, PROM, Flash, etc.): Memory chips are used to store data and information. They can be subdivided into static random access memory (SRAM), dynamic random access memory (DRAM, LPDDRX), programmable read-only memory (PROM), flash memory, and embedded memory (Embedded Memory).
SRAM is used to store data in electronic products, maintaining data unchanged during power-on, but losing data after power-off; DRAM maintains data unchanged during power-on through periodic refreshing, but loses data after power-off; Flash maintains data unchanged during power-on and does not lose it after power-off; PROM retains data once written using special means, regardless of power state. The first two are classified as volatile memory, while the latter two are classified as non-volatile memory. These types of memory can be packaged as independent memory chips or designed within CPUs, MCUs, and SoCs, also known as embedded memory.
Figure 5. Examples of some memory chips
Depending on their purpose, different types of memory should be selected. For example, desktop computers generally save data on hard drives after power-off, thus using a lot of DRAM (DDR, LPDDRX, etc.), while smartphones need to use a lot of Flash chips to permanently retain data (such as contacts, photos, audio, and video).
4.System on Chip (SoC): A system on a chip integrates an entire electronic system onto a single chip. By providing power and a small amount of external circuitry to the SoC chip, a complete electronic product or system can be realized. For example, an audio/video player (MP4), car navigation system, or smartphone can all be implemented with a single SoC chip and a few external components. The internal structure of an SoC chip generally consists of a CPU core, embedded memory, and I/O interfaces (buttons, touch, USB, WiFi, etc.). SoC chips are designed as application-specific systems, such as those used in medical devices, automotive electronics, metering systems, smartphones, smart TVs, etc. SoC chips cannot be used across different fields like CPU chips; they are only applicable within their designated fields.
Figure 6. Examples of application-specific SoC chips
5.Microcontrollers(MCU): Microcontrollers are often referred to as single-board computers or microcontrollers, and they are a simplified version of general-purpose processors (CPUs). The simplification is reflected in several aspects, including processing word width, processor and instruction architecture, memory size, clock speed, etc. MCUs are generally used in simpler, smaller electronic products or systems to perform simple control and data processing tasks. However, in large systems, many MCUs can also complete complex control tasks. The applications of MCU chips are extensive, ranging from simple tasks like balcony timed watering devices, rice cookers, refrigerators, to medium applications like instruments, industrial automation production lines, and large applications such as high-speed trains and aircraft system control.
Systems built around MCUs or SoC chips are also referred to as embedded systems, and MCUs and SoCs are also known as embedded microprocessors.
There are many types of MCUs, with over 70 product series and more than 500 varieties. For example, MCS-51 series, PIC series, STM32 series, MSP430 series, TMS series, AVR series, STC series, etc. Within just the MCS-51 series, chips are divided into several specifications based on the number of clock cycles per machine cycle, with 12T chips including 8051, 8031, AT89C51, 8032, etc.; 6T chips include STC89 series, etc.; 4T chips include 80C320, W77E58, etc.; and 1T chips include STC series, etc. Additionally, there are different manufacturers and brands, leading to a vast number of chip models.
Figure 7. Examples of some MCU chips
6.Application-Specific Integrated Circuits (ASIC): If a user does not want to use general-purpose chips but instead wants to customize a chip according to their application requirements, this type of chip is called a fully customized chip. For example, the second-generation ID card chip is a typical example of ASIC. Some original equipment manufacturers customize ASICs for their products to avoid using general-purpose chips, first, to protect the technical details and know-how of their products; second, ASICs are more suitable for the needs of their products; third, as long as the product can be mass-produced, the high custom costs of ASICs can be amortized.
Figure 8. Examples of some ASIC chips
7.Programmable Logic Devices (PLD) (including PLD, PAL, GAL, FPGA, etc.): The first six types of chips are referred to as fixed logic circuit chips. Once produced by the foundry, their functions are fixed and cannot be significantly altered. If improvements or upgrades are needed, the design must be modified and sent back to the foundry for re-production. The cost of modification and re-production is very high, and only chips with high demand are developed in the fixed logic circuit mode.
Programmable logic devices (PLD) are produced by factories with undefined functions, and designers must program them according to requirements for the chip to exhibit the desired functions. Moreover, certain types of PLD chips can be programmed multiple times, making them very suitable for applications that require function refinement and upgrades, such as communication devices and mobile communication base stations.
Before programming, PLD chips are considered general-purpose chips, and manufacturers can mass-produce them to meet various application needs. After programming, they become specialized chips that only meet specific application needs in a particular field. Therefore, PLD chips are also referred to as semi-custom chips.
Figure 9. Examples of some programmable logic device chips
The most widely used type currently is the field-programmable gate array (FPGA), which is particularly suitable for applications with small quantities or larger quantities that require continuous refinement and upgrades. It has extensive applications in communications, security monitoring, automatic control, artificial intelligence, military and aerospace, as well as in chip design prototype verification, algorithms, and embedded system development.
People like to compare ASICs and PLDs because both ASICs and programmed PLDs are specialized custom chips. However, they have the following differences: first, the former is customized by designers and manufacturers, while the latter is programmed by users; second, the former’s functions cannot be altered after production, while the latter’s functions can be refined and upgraded after programming; third, the production cost of the former is very high, requiring mass production, while the latter has a low customization cost, suitable for use in small batch products.
2. Analog Circuit Chips
Analog circuits are used to detect, transmit, transform, process, and amplify analog signals. Components in analog circuits, in addition to transistors, also include diodes, resistors, capacitors, and inductors. Most transistors in analog circuits do not operate in a switching state like digital circuits, but instead work in a linear state. Analog circuit chips have many functions and varieties, making it difficult to categorize them. Compared to digital circuits, the design difficulty of analog circuit chips is higher, requiring longer technical accumulation and higher demands on designers. Therefore, designers of analog circuit chips and systems tend to receive higher salaries.
Note: The chip examples shown in this section provide internal structure diagrams, which may seem complex, but are actually much smaller in scale than digital chips (such as CPUs, GPUs, etc.), where the number of transistors can reach hundreds of billions, making it impossible to depict the transistor-level structure, and only larger functional modules can be illustrated. Do not misunderstand that analog chips are more complex than digital chips.
1.Discrete Devices and Modules(diodes, transistors, MOSFETs, IGBTs, etc.): These devices and modules are also made using integrated circuit planar technology. Although they are packaged as devices and modules, their appearance does not resemble typical chips, they still fall within the category of integrated circuits. The number of components inside discrete devices is very small, but during design and manufacturing, the control of component parameters is extremely precise. Unlike digital circuits, where functionality is paramount, all analog circuits are parameter and performance-driven.
Figure 10. Examples of some discrete devices and modules
2.Power Circuits: Power circuits are used to convert 200V 50Hz AC power into different output voltages and currents of DC power, serving as the power supply for various electronic products and systems. There are many types of power circuit chips, with commonly used switching power supply chips alone numbering over 300 types (including more than 160 DC/DC chips; 60 AC/DC chips; 30 power controller chips; and 50 charging controller chips). It is estimated that there are no less than 500 existing power chip models.
Figure 11. Examples of some power chips
3.Signal Detection Circuits: Used to detect weak electrical signals, which are processed through filtering, amplification, and other front-end processing to become large signals or digital signals that are easier to handle.
Figure 12. Examples of some signal detection chips
4.Filters: Filter circuits are used for signal extraction, transformation, or anti-interference. They are a type of selective frequency circuit that allows specific frequency components of a signal to pass while greatly attenuating other frequency components. Thus, there are low-pass, band-pass, and high-pass filters, as well as passive and active filters. Filter chips are generally active filters.
Figure 13. Examples of some filter chips
5.Conversion Circuits: Conversion circuits are used to convert current signals into voltage signals or convert voltage signals into current signals; or to convert DC signals into AC signals or vice versa; or to convert DC voltage into a frequency proportional to it, etc. Switching power supplies, voltage regulators, level shifters, and analog-to-digital conversion circuits (ADC/DAC) also belong to conversion circuits. ADC/DAC are classified as mixed-signal circuits, hence discussed in the third section.
Figure 14. Examples of some conversion circuit chips
6.Signal Generators: Signal generating circuits are used to produce sine waves, square waves, triangular waves, sawtooth waves, etc. They mainly include various function signal generators, special frequency, waveform, and pulse signal generators, among others. The types of signals generated by signal generators are continuously increasing based on application needs.
Figure 15. Examples of some signal generator chips
7.Amplifiers: Amplifier circuits are used to amplify the voltage, current, or power of signals. They mainly include preamplifiers, operational amplifiers, and power amplifiers (PA), among more than ten types of amplifiers. Depending on the signal frequency, they can also be categorized into low-frequency, medium-frequency, high-frequency, and RF types. Moreover, due to varying application scenarios, different performance requirements lead to different amplifier names.
Figure 16. Examples of some amplifier chips
3. Mixed-Signal Circuits
1.Analog-to-Digital Converters (ADC, DAC): Analog-to-digital converters (ADC) and digital-to-analog converters (DAC) serve as the circuit interfaces between the real world and the digital world. Without these chips, there would be no digital world today. These types of chips can be subdivided into many varieties based on channel count, conversion bit width, conversion rate, precision, etc., resulting in a vast number of chip models.
Figure 17. Examples of some ADC and DAC chips
2.Optoelectronic Conversion Circuits: Optoelectronic conversion chips are essential for implementing optical communication and optoelectronic systems. This includes optoelectronic coupling devices, photodetector diodes, phototransistors, and photoresistors.
Figure 18. Examples of some optoelectronic conversion circuit chips and devices
3.Baseband Circuits: Mobile baseband chips mainly consist of microprocessors, channel encoders, digital signal processors, modems, and interface modules. They are used to synthesize the baseband signals to be transmitted or decode the received baseband signals. Currently, only a few companies, including Qualcomm, Intel, Samsung, Huawei, MediaTek, Spreadtrum, and ZTE, can design and produce baseband chips.
Figure 19. Examples of some baseband chips
4.Modulators and Demodulators: Modulation and demodulation chips are designed to perform modulation, demodulation, or both functions. Modulation involves converting a varying baseband signal into a corresponding varying carrier amplitude (amplitude modulation), frequency (frequency modulation), or phase (phase modulation). Demodulation involves converting a varying carrier amplitude, frequency, or phase back into the corresponding varying baseband signal. Modulation and demodulation chips are widely used in radio transceivers, wireless broadcasting, wireless communication, broadband networks, and fiber optic networks.
Figure 20. Examples of some modulation and demodulation chips
5.Interface Circuits: Interface circuits connect and convert signals between internal components, between chips, between chips and the outside world, and between systems. They play an essential role in system construction.
Figure 21. Examples of some interface circuit chips
7.Sensors: Sensors are used to measure and perceive various physical quantities in the real world, such as magnetic force, motion, pressure, temperature, humidity, images, sounds, etc. Sensors come in many varieties and typically exist in the form of devices rather than chips, even if there are chips, they are generally encapsulated within devices.
Figure 22. Examples of some sensor chips
8.Drivers: Driver chips and devices come in many varieties, from small LED and LCD drivers to medium motor drivers and semiconductor lighting drivers, to large power switch drivers, electric vehicles, and locomotive power drivers, with a wide variety of types and numbers.
Figure 23. Examples of some driver chips
4. Special Circuit Chips
1.Radiation-resistant Military Aerospace Circuits: Aerospace-grade chips must not only exceed military-grade chips in working temperature (-55℃ to 125℃) but also meet radiation resistance requirements. Military aerospace-grade chips typically use ceramic packaging and protective shielding. These chips must perform excellently in terms of functionality, performance, temperature, radiation resistance, and reliability. Due to high monopoly levels and relatively low demand, it is said that some chips can cost between 500,000 to 5 million yuan each.
Figure 24. Examples of some military aerospace-grade chips
2.RF Power Circuits: As people continuously pursue wireless communication speed and quality, RF power circuit chips and devices for wireless transmission have increasingly stringent requirements. These chips and devices belong to analog circuits and can be considered the crown jewels of chips; only through long-term research and development investment and technical accumulation can they be achieved, with no shortcuts available.
Figure 25. Examples of some RF power circuit chips and devices
3.Ultra-high Voltage High Power Circuits: Silicon power devices are still widely used in applications below 600V due to their low cost. However, if voltage requirements increase further, especially in cases requiring higher efficiency and temperature, chips and devices made from wide bandgap materials such as SiC must be used.
Figure 26. Examples of some ultra-high voltage high power circuit chips and devices
Conclusion: The classifications in this article are rough and approximate, and the chip and device examples provided may not be the most representative. Each major category should also have additional subcategories. Perfection cannot be pursued; one can only grasp the big picture and let go of the small details, roughly sketching the “appearance” of the chip family. I hope this helps you understand chips. Writing is not easy; if you find this article good, please give it a thumbs up. If you think it is not good, please criticize it, but please hold it high and drop it gently. Thank you!
