- What is a "signal chain chip"? We live in an analog world: signals such as sound, voltage, temperature, pressure, and light intensity are all changing continuously. However, most electronic systems - such as mobile phones, smart watches, industrial controllers, and unmanned driving systems - ultimately process and store information using digital logic (0 and 1). The signal chain chip is an intermediary system between this "analog world" and the "digital world". It is responsible for receiving external analog signals, amplifying, filtering, converting, conditioning, and other processing, and finally converting the signal into a data format that can be processed by the digital system.It can be understood as follows: the signal chain is a "pipeline" that receives signals from sensors, filters out impurities, enhances weak signals, transforms signal formats, and then hands over clean signals to MCU, DSP or AI chips for processing. This entire process is called a "signal chain", and the key IC responsible for this process is called a "signal chain chip". 2. Components of a signal chain chip The signal chain chip is not a single device, but a collection of multiple functional modules, usually including the following categories: 1. Linear Devices - Operational amplifiers (Op-Amp) precisely amplify weak voltage signals, such as microphones, electrochemical sensors, current detection and other occasions.What we pursue is high gain, low noise, low distortion, and low offset. - Comparator is used to compare the size of two voltage signals and output a high or low level. For example, temperature exceeds the threshold alarm, battery voltage is too low protection, logic trigger, etc. all need comparators. - Analog switch / multiplexer (MUX) is used to switch channels between multiple analog signals. For example, if a chip needs to collect 8 sensor signals, MUX is required to select channels in turn. 2. Signal conversion device - ADC (analog-to-digital converter) converts analog signals into digital signals and is a key device for the transition of signal chain to digital processing. For example, analog information such as temperature, voltage, image, sound, etc. must enter the digital domain through ADC.There are many types of ADCs, such as SAR, ΔΣ, and Pipeline, which are suitable for different precision and speed scenarios. - DAC (digital-to-analog converter) converts digital signals into analog signals and is often used in audio playback, waveform output, voltage control, and other occasions. Like ADC, it is also a bridge between the analog and digital worlds. 3. Interface and conditioning circuits - Signal conditioners (Signal Conditioning ICs) are used for signal preprocessing, such as filtering, gain adjustment, zero drift correction, anti-interference, etc. Sometimes they are modular packages, and sometimes they are integrated in sensors or ADCs.- Isolator (Isolation IC) In industrial, medical or high-voltage environments, the signal channel needs to be electrically isolated for safety or to prevent interference. Common isolation methods include optocouplers, magnetic couplings, capacitive couplings, etc. - Sensor interface chip (Sensor Interface IC) Some sensors output very weak or irregular signals (such as RTD, thermocouples). This type of interface chip is responsible for signal conditioning, calibration, and standardization. 3. The workflow of the signal chain chip Suppose we want to collect the signal of an industrial temperature sensor (thermocouple) and upload it to a microcontroller. The process of the entire signal chain may be as follows: Signal acquisition: The thermocouple generates a weak millivolt voltage.Amplification: Use a low-noise op amp for voltage amplification. Filtering: Use a bandpass filter to remove high-frequency noise and low-frequency drift. Isolation protection: Use optocouplers or magnetic isolators to prevent the system from posing risks to people or the main control chip. Analog-to-digital conversion: The ADC converts the processed voltage signal into 12-bit or 16-bit digital data. Data output: The digital signal is sent to the MCU and uploaded to the system main control platform through the I2C, SPI or UART interface. This complete path constitutes a standard "signal chain". 4. Key performance indicators of signal chain chips Each signal chain device has its own performance indicators.However, the key points of the entire system are as follows: Index name Meaning Resolution The number of bits of the ADC or DAC determines the accuracy of the output Sampling rate The number of times the data is collected or output per second, which is related to the dynamic performance Gain The error range of the precision amplifier affects whether the signal is distorted after amplification Input offset voltage The error of the op amp in the absence of input Noise density The size of the random noise affects the system SNR (signal-to-noise ratio) Common mode rejection ratio (CMRR) The ability to suppress common mode interference Power supply rejection ratio (PSRR) The ability to affect the output due to power supply fluctuations Temperature drift Performance fluctuations caused by temperature changes Package size and power consumption are especially important in portable devices or industrial dense wiring systems.5. Application fields of signal chain chips Signal chain chips are used in almost all electronic systems that need to "perceive the physical world". The following is a typical industry classification: Application fields Usage scenarios Medical electronics Electrocardiogram (ECG), blood oximeter, body temperature detection, CT image acquisition Industrial control PLC system, industrial robot, current/voltage monitoring, pressure acquisition Automotive electronics Automotive cameras, lidar, tire pressure monitoring, temperature sensor interface Smart home Air quality detection, environmental temperature and humidity perception, smoke alarm Consumer electronics Voice recognition (microphone front end), audio playback (DAC), camera image preprocessing Aerospace High-reliability sensor interface, isolation ADC, radiation-resistant signal conditioning6. Technical Difficulties and Design Challenges of Signal Chain Chips Compared with pure digital circuits, signal chain chip design challenges are more for the following reasons: 1. High requirements for signal authenticity and integrity If a weak signal is amplified with too much noise or distortion, it may lead to subsequent system misjudgment, and even cause systemic accidents in serious cases. 2. Circuits are sensitive to the environment. The op amps, ADCs and other devices in the signal chain are very sensitive to temperature, power supply fluctuations, and electromagnetic interference. Redundancy, shielding, calibration and other means are required during design. 3. The test verification cycle is long. A large number of measurements must be made under different input signals, temperatures, and power supply conditions to verify whether the performance is stable. This is much more complicated than relying on logic simulation alone for digital chips.4. EDA support is limited, and manual workload is high. Most designs require engineers to manually select devices, layout capacitors and resistors, and optimize parameters. The degree of automation is far lower than that of digital circuit design. VII. Signal chain chip market trends and development directions 1. The signal chain chip market continues to grow. With the popularization of industrial automation and smart devices, the application of sensors continues to increase, which has led to a continuous demand for signal chain chips. The global analog chip market has grown steadily every year, with the signal chain being one of the main growth drivers. 2. The integration level is getting higher and higher. The previously dispersed op amps, ADCs, and interface modules are now gradually integrated into a SoC to form a highly integrated "signal chain front-end chip" (AFE).It is convenient for customers to develop systems quickly. 3. High precision and low power consumption are equally important. The Internet of Things, wearable devices, smart terminals, etc. have extremely high requirements for chip accuracy, power consumption and size, which promotes the development of signal chain chips in the direction of "ultra-low power consumption + high performance". 4. The pace of domestic substitution is accelerating. The core market of signal chain chips has long been monopolized by international manufacturers such as TI, ADI, and Maxim. In recent years, domestic companies such as Shengbang Micro, Xinhai Technology, Awin Electronics, Nanochip, and SiRuiPu are gradually rising, and gradually realizing localization in subdivided fields such as operational amplifiers, ADCs, and isolators.8. Conclusion: Signal chain chips are the translators of the analog world. Signal chain chips are not dazzling and are not noticed by most end users, but they are an indispensable "sensory organ" in electronic systems. Every sound, every temperature, and every change in current are transmitted to the digital world by signal chain chips. For integrated circuit engineers, designing a stable, accurate, and low-noise signal chain system is a must.It is a job that tests both the depth of knowledge and the breadth of experience. From device modeling, simulation, layout design, to final test verification, every detail may affect the quality of the entire signal chain. With the development of industries such as artificial intelligence, industrial control, and smart medical care, signal chain chips will become increasingly important. It is no longer just a supporting role, but the cornerstone of the intelligent system's "hearing, seeing, and measuring".
