Oscillator BIST Averaging for Phase Noise Mitigation in ADPLLs
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Solution Overview
Problem
Production and field testing of ADPLLs is complex, resource-intensive, and prone to noise interference, making it difficult to detect parametric failures and counteract measurement noise effectively.
Innovation Solution
A built-in self-test (BIST) mechanism that provides a reliable test of an oscillator circuit, which integrates a system 100 including a BIST circuit that measures the oscillator characteristics by averaging results from the oscillator circuit, which includes a BIST circuit that repeatedly sends control stimuli to the oscillator circuit, averages the resulting characteristics, and compares them to an oscillator model to detect errors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If external testing equipment is used to test ADPLLs, then measurement capability is provided, but device complexity and resource requirements increase
Solution Approach 1:
The ADPLL incorporates a built-in self-test (BIST) mechanism that enables the device to test its own oscillator characteristics without requiring external testing equipment. The BIST circuit generates test signals, measures oscillator parameters, and evaluates performance autonomously, thereby reducing device complexity while maintaining measurement capability.
Solution Approach 2:
The BIST circuit is integrated into the existing ADPLL architecture and serves multiple functions: it performs oscillator characteristic measurement, fault detection, and self-diagnosis. This multi-functionality eliminates the need for separate external testing equipment, reducing overall system complexity.
2Measurement precision
If measurement time is extended to improve resolution, then measurement precision improves, but noise accumulation increases
Solution Approach 1:
The BIST circuit employs a feedback mechanism where measured oscillator characteristics are continuously monitored and compared against expected values. When deviations indicating noise or failure are detected, the system adjusts measurement parameters or triggers re-measurement, thereby achieving high precision without excessive noise accumulation from prolonged measurement.
Solution Approach 2:
Instead of continuously measuring for extended periods, the BIST circuit performs multiple rapid measurements and uses statistical processing to achieve the required resolution. This partial action approach with repeated sampling provides sufficient precision while minimizing total measurement time and noise exposure.
3Measurement precision
If production testing is performed externally, then measurement capability is provided, but productivity and resource efficiency decrease
Solution Approach 1:
The integrated BIST mechanism enables autonomous testing of oscillator characteristics without requiring external test equipment or personnel. The device can perform self-diagnosis and fault detection independently, significantly improving productivity and resource efficiency during production and field operations.
Solution Approach 2:
The BIST circuit performs testing operations during manufacturing and initial system setup, identifying potential failures before the device is deployed. This preliminary action eliminates the need for time-consuming external testing later, improving overall productivity.
4Measurement precision
If oscillator characteristics are measured repeatedly to average noise, then measurement precision improves, but measurement time increases
Solution Approach 1:
The BIST circuit performs multiple rapid measurements and uses statistical averaging to achieve the required precision. By conducting a limited number of repeated measurements rather than continuous prolonged measurement, the system achieves sufficient accuracy while minimizing total measurement time through efficient sampling and processing.
Data Source
AI summary
A phase locked loop (PLL) includes an oscillator circuit and a built-in self-test (BIST) circuit. The BIST circuit tests the oscillator circuit by providing a set of input signals to the oscillator circuit and averages resulting output signals to generate an average oscillator characteristic. In some embodiments, the input signals are repeatedly sent to the oscillator circuit during a measurement window. The BIST circuit compares the resulting average oscillator characteristic to an oscillator model and determines whether the oscillator circuit is experiencing a failure based on how well the average oscillator characteristic matches the oscillator model.