Semiconductor Trimming Circuit with Pseudo-Value Correction
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Solution Overview
Problem
Conventional trimming methods for semiconductor devices, such as those used in liquid crystal display drivers, fail to achieve high precision due to manufacture tolerance in trimming circuits, leading to non-uniform output values despite attempts to adjust them to target values.
Innovation Solution
A semiconductor device with a trimming value setting circuit that includes a register for volatile pseudo-trimming values and non-volatile storage for final trimming values, using a correction table to adjust output values to targets, and a selector to choose between pseudo and final trimming values, addressing the tolerance issues through precise value correction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a conventional trimming method is used to adjust output values to target values, then trimming precision is improved, but manufacture tolerance of the trimming circuit causes the trimming-after output value to deviate from the target value
Solution Approach 1:
The patent applies preliminary action by measuring the trimming-before output value and calculating the trimming value in advance using a trimming table, then applying this pre-calculated trimming value to adjust the output. This preliminary adjustment compensates for manufacturing variations before the actual trimming process, improving both trimming precision and output uniformity despite trimming circuit tolerances.
Solution Approach 2:
The patent implements feedback by measuring the trimming-after output value and comparing it with the target value, then calculating a correction value based on the deviation. This feedback mechanism allows the system to detect and correct errors caused by trimming circuit manufacture tolerance, ensuring the final output value meets the target specification.
2Ease of manufacture
If a trimming circuit with manufacture tolerance is used, then ease of manufacture is improved, but the trimming-after output value becomes non-uniform
Solution Approach 1:
The patent applies parameter changes by introducing correction values that modify the original trimming values based on measured deviations. The correction value is calculated as the difference between the target value and the actual trimming-after output value, and this correction parameter is applied to adjust subsequent trimming operations, maintaining output consistency despite variations in trimming circuit parameters.
Solution Approach 2:
The patent uses an intermediary approach by introducing a correction value as a mediating parameter between the trimming circuit output and the target value. This correction value acts as a buffer that compensates for the manufacturing tolerance of the trimming circuit, allowing the system to achieve precise output control without requiring high-precision trimming circuit components.
3Measurement precision
If multiple trimming processes are implemented to correct for tolerance, then trimming precision is improved, but productivity decreases due to additional measurement and calculation steps
Solution Approach 1:
The patent merges the trimming-before measurement, trimming value calculation, and trimming-after verification into an integrated trimming process. By combining these steps and using the correction value to adjust the original trimming value, the system achieves high trimming precision while reducing the number of separate iterative trimming cycles required, thereby improving productivity in shipment testing.
Data Source
AI summary
A semiconductor device includes: a trimming object circuit configured to use a trimming circuit to adjust an output based on a trimming value; and a trimming value setting circuit configured to set the trimming value. The trimming value setting circuit includes: a register configured to volatilely store a pseudo-trimming value set with reference to a trimming table such that an output value of the trimming object circuit becomes equal to a target value; a trimming value storage configured to non-volatilely store a final trimming value, wherein the final trimming value is set by correcting the pseudo-trimming value with reference to a trimming value correction table such that the output value of the trimming object circuit, which is obtained based on the pseudo-trimming value, becomes equal to the target value; and a selector configured to select one of the pseudo-trimming value and the final trimming value as the trimming value.