A built-in self-test architecture for automated analog circuit characterization and adaptive compensation

Background

The field of analog and mixed-signal circuit testing is critical in the design and manufacturing of modern integrated circuits, particularly as systems-on-chip (SoCs) increasingly combine digital logic with sensitive analog and RF components. As devices become more complex and miniaturized, ensuring the performance and reliability of embedded analog blocks—such as amplifiers, filters, and data converters—has become a significant challenge. Traditional analog testing requires precise measurement of parameters like gain, phase, linearity, and signal-to-noise ratio, all of which are susceptible to variations in process, voltage, and temperature. The need for efficient, automated, and cost-effective test solutions is further driven by the high production volumes and stringent quality requirements in consumer electronics, communications, and automotive applications.

Current approaches to analog testing are often manual, expensive, and time-consuming, relying heavily on external test equipment and specialized setups. This reliance not only increases manufacturing costs but also limits the feasibility of comprehensive testing, especially for low-cost or high-volume products. Moreover, conventional test methods typically require significant analog hardware overhead and may not be easily scalable or integrable into digital-centric design flows. Techniques such as Fast Fourier Transform (FFT)-based spectral analysis, while powerful, demand substantial computational resources and may not be practical for on-chip implementation. As a result, many analog circuits are inadequately tested, leading to potential field failures and reduced yield. There is a pressing need for integrated, automated test architectures that can provide thorough analog characterization without incurring prohibitive area, cost, or complexity penalties.

Technology

This technology is a built-in self-test (BIST) solution for analog and mixed-signal circuits that integrates a direct digital synthesizer (DDS)-based test pattern generator (TPG) and a digital output response analyzer (ORA) within the device or its supporting digital logic, such as an FPGA or ASIC. The TPG uses DDS circuits to generate highly precise and programmable digital waveforms—including single-tone, two-tone, and complex modulated signals—which are converted to analog and applied to the device under test (DUT). The DUT’s analog output is then digitized, and the ORA processes this signal by multiplying it with a reference waveform from the DDS and accumulating the result. This accumulation yields a DC value proportional to the signal power at the reference frequency, enabling efficient extraction of spectral information without the need for a Fast Fourier Transform (FFT). The system supports automated measurement of key analog parameters such as gain, phase, linearity (IM3/IP3), and signal-to-noise ratio (SNR), and is designed for seamless integration into ASICs or FPGAs, facilitating comprehensive on-chip testing and adaptive compensation.

What differentiates this technology is its innovative use of DDS-based waveform generation combined with a multiplier/accumulator approach for spectral analysis, which eliminates the need for resource-intensive FFT computations. This architecture minimizes the impact on analog circuitry by leveraging existing DAC/ADC resources and confines most of the additional logic to the digital domain, making it highly efficient and scalable for integration in modern semiconductor devices. The flexibility of the TPG allows for a wide range of test signals and modulation types, supporting thorough analog characterization and enabling adaptive compensation for process, voltage, and temperature variations. Additionally, the system’s ability to time-share the ORA using multiplexers reduces area overhead, making it a cost-effective solution for automated, real-time, and in-system analog testing across manufacturing, deployment, and field scenarios.

Benefits

• Enables automated, comprehensive testing of analog parameters such as gain, phase, linearity (IM3/IP3), and signal-to-noise ratio (SNR).
• Uses a DDS-based test pattern generator to produce precise and flexible waveforms, including complex modulated signals.
• Employs a multiplier and accumulator-based output response analyzer for efficient spectral extraction without requiring FFT, reducing hardware complexity.
• Supports on-chip integration in ASICs or FPGAs, facilitating in-system, manufacturing, and field testing with minimal additional analog circuitry.
• Allows adaptive compensation and calibration for process, voltage, and temperature variations based on measured parameters.
• Reduces test time and area overhead through multiplexing and time-sharing of analysis resources.
• Provides accurate phase and gain measurements by using sine and cosine reference waveforms and phase-offset accumulation techniques.
• Enables cost-effective and scalable analog testing suitable for RFICs, baseband systems, and mixed-signal circuits.

Applications

• On-chip analog/RF circuit testing
• Automated manufacturing test systems
• In-system self-calibration for ASICs
• Field diagnostics for mixed-signal devices
• Adaptive compensation in wireless transceivers

Additional info

This built-in self-test architecture for analog circuits employs a direct digital synthesizer (DDS) as a test pattern generator and a digital output response analyzer (ORA). The DDS creates precise waveforms, applied to the Device Under Test (DUT) via a DAC. The DUT’s digitized output is multiplied by a reference and accumulated by the ORA, yielding DC values for efficient spectral analysis. This enables automated measurement of gain, phase, linearity, and SNR.