Analog ASICs for Authentication Devices: Design Guide & Security Applications

December 19, 2025

Analog ASICs play a critical role in authentication devices by enabling high-precision signal processing, low-power operation, and advanced hardware security functions such as PUF (Physically Unclonable Function). This article explains what analog ASICs are, their key design considerations, how they support security features, and future trends in authentication system development.

What are Analog ASICs in Authentication Devices?

In authentication devices, analog ASICs are a core component for accurately and stably processing signals from sensors. When it comes to applications such as biometric authentication and physical token authentication, it is necessary to acquire analog signals such as fingerprints, veins, or voltage changes with high precision and bridge them to the subsequent digital authentication processing. It is possible to obtain low noise and power saving, which are difficult to achieve with a combination of general-purpose ICs, thanks to application-specific analog ASICs. Highly integrated design allows for both miniaturization and high reliability, maintaining a high security level even in edge applications.

Authentication devices have diverse applications, including biometric authentication equipment, access control systems, and security modules for IoT. All of them require high-precision input signal processing and fraud detection. For this purpose, they use a system configuration integrating sensors, amplifiers, filters, A/D conversion circuits, and authentication logic. The front-end section that handles analog signals is the key element that determines the authentication accuracy and responsiveness of the entire system, and this is where manufacturers use the specialized design technology of analog ASICs.

Analog ASICs can integrate diverse functions such as amplification circuits and filtering circuits, A/D conversion circuits, which are the starting points of signal processing, as well as temperature compensation and reference power supply circuits. The optimization of these circuits stably handles minute signals from external sensors and significantly influence the system’s sensitivity and security accuracy. Furthermore, by adding product-specific operating characteristics, they also fulfill the role of individual identification functions for authentication and acting as a trust anchor. Such integrated circuits enable overall performance enhancement and differentiation of the design.

Key Design Considerations

In a discrete configuration, signal processing is realized by combining multiple analog ICs and passive components. This results in design load factors such as increased complexity of board design, more noise sources, and increased trimming effort. In contrast, analog ASICs integrate the necessary circuits onto a single chip, making it possible to improve the matching accuracy between circuits and enable a design optimized in terms of both area and power consumption. Moreover, specialized design for specific applications allows for the reduction in the number of components and improvement in reliability, which is advantageous from the perspective of manufacturing cost and quality control.

Signal Accuracy & Low-Noise Design

The analog ASIC design process begins with defining specifications to achieve optimal characteristics for each application, proceeding through topology selection, circuit design, layout, and verification before reaching manufacturing. Especially for authentication applications, signal integrity and reproducibility, environmental resistance, and minimizing differences between products are crucial. Since general IP reuse is often difficult, circuit configurations are frequently designed individually. This demands close cooperation between circuit design at the transistor level and physical layout, making design judgment backed by experience indispensable.

The design specification begins with clearly defining the required accuracy, operating voltage, temperature range, bandwidth, and noise tolerance of the target authentication device. The step following this, is to identify necessary circuit blocks (amplifier, ADC, reference voltage, power management, etc.) and select the architecture based on their respective performance requirements. For security applications, industries require circuits that show consistent performance even against power supply fluctuations and temperature changes, making the introduction of variation control technology and offset cancellation technology important.

In layout design, noise suppression technology is indispensable to prevent performance degradation caused by crosstalk, parasitic elements, power supply ripple, and so on. Analog circuits are more sensitive than digital circuits, and physical structures such as GND impedance, wiring length, and opposing area affect operation, requiring a careful floor plan. Furthermore, for security applications, countermeasures against information leakage at the layout level (e.g., differential signaling or side-channel resistance design) are also crucial design elements from the perspective of physical attack resistance.

After design completion, operation confirmation is performed through simulation and silicon evaluation. However, the operating point of analog circuits tends to change easily depending on the environment and manufacturing lot, and results often deviate from theoretical predictions. Therefore, in the verification phase, corner simulation, Monte Carlo analysis, and temperature/voltage variation tests using actual devices become important. Researchers and designers utilize high-precision probing technology and automated measurement systems for measurement, aiming to shorten the development period and improve the accuracy of design feedback.

Power Efficiency & Low-Power Architecture

Security functions usually require continuous operation or continuous monitoring, making increased power consumption a design challenge. Especially in battery-powered edge devices and wearable devices which must maintain a robust authentication process while achieving operation below the milliwatt level. Analog ASICs can meet these requirements by introducing dedicated power control circuits and low-power architectures. Experts expect designs equipped with secure standby modes and on-demand authentication functions to become the mainstream.

Security Features Enabled by Analog ASICs

In hardware-based authentication technology, physical identification methods utilizing individual differences in analog signals or natural noise are attracting attention. These technologies have higher clone resistance compared to conventional digital authentication. Anti-cloning methods such as PUF (Physically Unclonable Function) and analog scrambling are being put into practical use. Analog ASICs are the ideal platform for integrating these functions with high precision and low power consumption. In authentication based on sensor signals, the performance of separating noise and signals is crucial, requiring advanced knowledge of analog design.

PUF & Hardware Authentication

PUF is a mechanism that generates unique identification information using the variations on the silicon or natural differences in circuit characteristics. Manufacturers use this technology as a device-specific fingerprint, realizing a highly secure authentication method that does not require the storage of secret keys, also known as biometric authentication signal processing. In analog ASICs, bias control and compensation techniques are important for intentionally incorporating circuit variations into the design to obtain stable PUF responses. PUF has widespread applications, including token authentication, secure boot of IoT devices, and tamper detection. Hardware authentication ASIC allows enhanced security for many products.

Analog Scramble & Tamper Resistance

Analog scrambling is a technique that makes unauthorized reading or tampering from the outside difficult by adding specific modulation or randomization processing to the sensor output signal. This method achieves high security because the input signal possesses irreproducible randomness and generates unpredictable responses. Analog ASICs can implement this processing in real-time, strengthening security without compromising authentication accuracy. The design closely involves modulation circuits, random number generators, and decoding logic.

Verification & Testing Strategies

Sensor devices have slightly different response characteristics, even within the same part number, due to manufacturing variations and material properties. While these differences are usually treated as variations, engineers can conversely use them as identification information in authentication applications. Designs are progressing that use features such as response characteristics at specific frequencies, voltage response during temperature changes, and capacitance fluctuations for individual authentication and verification of authenticity. Analog ASICs provide the optimal components for detecting and processing these individual differences.

As security technology evolves, the design requirements for analog ASICs are becoming more advanced and diverse. Particularly in authentication functions within the fields of IoT and edge computing, power efficiency, real-time processing capability, and resistance to external attacks are required simultaneously. Analog ASICs are expected to increase in importance as a means of providing high design flexibility and circuit optimization to meet these complex requirements. The compatibility between flexible custom design and mass production capability will be the key to future product competitiveness.

When designing analog ASICs, it is necessary to proceed systematically and consistently with elements such as specification clarification, optimal selection of circuit blocks, noise countermeasures, layout strategy, and verification using actual devices. For authentication applications, designers must consider elements such as tamper resistance for security functions and the stability of PUF responses from the initial design stages. In implementation, ensuring reproducible operating characteristics and the ability to handle manufacturing variations are crucial. Systematic design based on these considerations is the key to success.

In recent years, various authentication methods such as biometric authentication, cryptographic tokens, PUF, and physical trust-based methods coexist, and the combined use of multiple methods is advancing. Analog ASICs require high configuration flexibility and expandability. For example, architectures that can accommodate multiple specifications during the design stage, such as changing the type of sensor input, adjusting the filter bandwidth, and varying the output format, are demanded. Flexible multi-modal support is precisely what differentiates the design capabilities of next-generation authentication equipment.

Future Trends & Challenges

Analog ASIC design is a field requiring advanced analog circuit theory and practical layout technology, and it faces the challenge of containing many individual-dependent elements supported by years of experience. Training young engineers has become difficult, making the inheritance and standardization of design know-how and the sophistication of design support tools urgent tasks. The utilization of model-based design and AI-supported layout technology is beginning. Introducing these will reduce dependence on individual expertise and establish highly reproducible design flows, which will contribute to future competitiveness.

In authentication devices, analog ASICs are a critical presence that handles the signal processing—the core of security—at the physical layer. They realize diverse processing such as acquisition of minute signals from sensors, removal of disturbances, and characteristic extraction for individual identification, all with low power consumption and high precision. Reliable integrated design enables device miniaturization and high integration, expanding the range of applications to mobile terminals and edge nodes. Appropriate design and utilization of analog ASICs lead to improved competitiveness for authentication equipment overall.

As various fields such as IoT, mobile, and industrial equipment require authentification functions, analog ASICs will demand more sophisticated and flexible designs. Designers need a comprehensive design perspective that considers not just the optimization of circuit operation but also the security level and operating environment. Understanding and introducing new technologies like PUF and analog scrambling and establishing efficient development systems through the utilization of design tools and human resources, will be key differentiators in future authentication device design.