Trimming Acceleration Circuit for Bandgap Voltage References
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Solution Overview
Problem
The existing methods for calibrating bandgap circuits in integrated circuits are time-consuming and require a large number of high-accuracy measurements, which is inefficient and costly, especially in industries with tight voltage regulation specifications.
Innovation Solution
A production test trimming acceleration circuit that uses a search algorithm to quickly identify suitable trim codes for voltage reference circuits, reducing the need for extensive measurements and improving noise rejection, allowing for faster and more accurate trimming.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional voltage measurement and trimming methods are used, then measurement accuracy can be maintained, but test time becomes excessively long
Solution Approach 1:
The patent replaces conventional voltage measurement methods with a time-based measurement approach. Instead of measuring voltage directly and calculating trim codes, the system measures the time it takes for an integrator to charge or discharge through a resistor. This time measurement is then used to determine the appropriate trim code. The substitution of voltage measurement with time measurement maintains accuracy while significantly reducing test time.
Solution Approach 2:
The patent changes the measurement parameter from voltage to time. By measuring the time required for the integrator to reach a threshold voltage level, the system indirectly determines the resistor value and corresponding trim code. This parameter transformation allows for faster measurements since time can be measured more quickly and with higher resolution than voltage, thereby reducing overall test time while maintaining precision.
2Manufacturing precision
If extensive voltage measurements are performed to achieve accurate trimming, then trimming accuracy is improved, but test cost increases
Solution Approach 1:
The patent replaces multiple expensive voltage measurements with a single time measurement. The time-based measurement approach requires fewer tester interactions and less complex measurement circuitry, thereby reducing test cost while maintaining trimming accuracy. The integrator-based time measurement can be implemented with simple circuitry that is already present in most ICs, eliminating the need for expensive external measurement equipment.
3Manufacturing precision
If traditional trimming algorithms are used, then comprehensive calibration can be achieved, but noise rejection is insufficient
Solution Approach 1:
The patent replaces voltage-based measurement with time-based measurement, which inherently provides better noise rejection. Time measurements are less susceptible to voltage noise and interference because they integrate the signal over a period rather than capturing instantaneous voltage levels. The integrator circuit averages out high-frequency noise during the charging/discharging process, providing cleaner measurement data for calibration.
Solution Approach 2:
The patent uses periodic charging and discharging cycles of the integrator to perform multiple measurements and determine the trim code. By repeating the measurement process over several cycles and analyzing the results, the system can filter out noise and identify the true signal, thereby improving both calibration accuracy and noise immunity simultaneously.
Data Source
AI summary
Systems and methods for production test trimming acceleration. In an illustrative, non-limiting embodiment, a method may include providing a first trim code to a reference circuit, where the reference circuit is configured to output a first signal in response to the first trim code; integrating a difference between the first signal and a target voltage value into a first integrated value; providing a second trim code to the reference circuit, where the reference circuit is configured to output a second signal in response to the second trim code; integrating a difference between the second signal and the target voltage value into a second integrated value; and adjusting at least one of the first or second trim codes in response to a comparison between the first and second integrated values.