Oscillator BIST Circuit for Resonator Testing With Fewer Pins
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Solution Overview
Problem
State-of-the-art oscillator circuits in wafer-level chip-scale packaging (WLCSP) lack commercially viable access to test points for resonating elements, making it difficult to detect failure modes such as resistance level dependency (RLD) and drive level dependency (DLD), which are crucial for improving long-term reliability.
Innovation Solution
Incorporating a built-in self-test (BIST) circuit within the oscillator circuit that selectively couples to the resonator's terminals during operation to test performance characteristics like RLD and DLD, allowing for efficient detection of failure modes within the chip-scale package, even when the oscillator is partially disabled.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If wafer-level chip-scale packaging (WLCSP) is used to reduce package size, then miniaturization is achieved, but access to test points for resonating elements is lost
Solution Approach 1:
The patent merges the resonator and oscillator circuit into a single integrated WLCSP package, with the resonator mounted directly on the oscillator circuit substrate. This integration eliminates the need for separate test point access while maintaining testing capability through the integrated BIST circuitry that can probe the resonator through shared circuit paths.
Solution Approach 2:
The built-in self-test (BIST) circuit performs automated testing of the resonator without requiring external test equipment or additional test pins. The BIST circuit uses the existing oscillator circuit components and pathways to conduct resistance level dependency (RLD) and drive level dependency (DLD) measurements, enabling the device to test itself during manufacturing and application.
2Quantity of substance
If the number of functional pads is minimized in WLCSP, then pin count is reduced, but direct connection to resonating element for testing is eliminated
Solution Approach 1:
The oscillator circuit pads serve dual functions: they connect the resonator to the oscillator circuit for normal operation and provide test access points for the BIST circuit. The same circuit pathways used for signal generation are utilized for RLD and DLD measurements, eliminating the need for dedicated test pins while maintaining full testing capability.
Solution Approach 2:
The BIST circuit acts as an intermediary that enables testing through the existing functional pads. Rather than requiring direct external access to the resonator, the BIST circuit mediates the measurement process by coupling to the resonator through the oscillator circuit's existing signal paths, allowing indirect but effective testing through minimal pads.
3Device complexity
If resonator testing is performed through functional testing of oscillator circuits, then testing is simplified, but failure modes like RLD and DLD cannot be detected
Solution Approach 1:
The BIST circuit dynamically switches between different testing modes (RLD and DLD) by adjusting the coupling configuration to the resonator. During RLD testing, the circuit measures resistance at different drive levels, and during DLD testing, it measures drive level effects on resonator performance. This dynamic reconfiguration enables comprehensive failure mode detection without requiring separate static test circuits.
Solution Approach 2:
The BIST circuit changes operating parameters (drive level, frequency, power) to detect failure modes that are invisible under normal operating conditions. By varying the drive level and measuring the resonator's response, the system can detect RLD and DLD failure modes that would not manifest during standard functional testing at fixed operating points.
Data Source
AI summary
Packaged integrated circuit devices include an oscillator circuit having a resonator (e.g., quartz crystal, MEMs, etc.) associated therewith, which is configured to generate a periodic reference signal. A built-in self-test (BIST) circuit is provided, which is selectively electrically coupled to first and second terminals of the resonator during an operation by the BIST circuit to test at least one performance characteristic of the resonator, such as at least one failure mode. These test operations may occur during a built-in self-test time interval when the oscillator circuit is at least partially disabled. In this manner, built-in self-test circuitry may be utilized to provide an efficient means of testing a resonating element/structure using circuitry that is integrated within an oscillator chip and within a wafer-level chip-scale package (WLCSP) containing the resonator.