Bandgap Reference Trim Circuit for Process-Tolerant Voltage Accuracy
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Solution Overview
Problem
Bandgap reference voltage sources in integrated circuits face tolerance errors due to imperfect silicon fabrication, leading to inaccuracies that affect the stability and accuracy of the reference voltage over environmental changes and time.
Innovation Solution
A bandgap reference voltage circuit is designed using a combination of complementary to absolute temperature (CTAT) and proportional to absolute temperature (PTAT) voltages, with a cascaded resistor network and switches for trimming, and a differential error amplifier with negative feedback to minimize tolerance errors and ensure stability and accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a bandgap reference voltage source is implemented using standard silicon fabrication processes, then the circuit can be manufactured with standard process capabilities, but tolerance errors occur due to imperfect fabrication which alter device parameters and reduce accuracy
Solution Approach 1:
The patent implements a trimming mechanism that uses feedback to detect and correct tolerance errors. The trimming circuit measures the actual reference voltage and adjusts device parameters (such as resistor values or transistor dimensions) to compensate for fabrication variations, thereby restoring accuracy while maintaining standard manufacturing processes
Solution Approach 2:
The patent employs parameter changes by allowing post-fabrication adjustment of circuit parameters through trimming. By modifying physical parameters such as resistance values or current ratios after manufacturing, the system compensates for fabrication tolerances and achieves the desired reference voltage accuracy
2Manufacturing precision
If trimming procedures are added to correct tolerance errors, then the accuracy of the bandgap reference is restored, but the device complexity increases due to additional trimming circuits and control mechanisms
Solution Approach 1:
The patent divides the trimming function into segmented, modular components that can be independently controlled. By segmenting the trimming circuit into discrete adjustable elements (such as switched resistor ladders or binary-weighted current sources), the system achieves accurate trimming while maintaining manageable circuit complexity through modular design
3Stability of the object's composition
If the bandgap reference is designed to be stable over temperature and supply voltage ranges, then the reference voltage remains constant under environmental changes, but the circuit requires complex compensation mechanisms to achieve this stability
Solution Approach 1:
The patent uses a composite approach by combining multiple voltage components with opposite temperature coefficients (such as CTAT and PTAT voltages) to create a reference voltage that is stable over temperature. This composite structure inherently compensates for temperature variations without requiring external compensation mechanisms, thereby achieving stability while managing circuit complexity
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution provides a stable and accurate reference voltage that is largely independent of temperature and manufacturing process variations, suitable for high-performance integrated circuits like system on a chip (SOC) applications.
Implementation Method 1
A bandgap reference voltage circuit is designed using a combination of complementary to absolute temperature (CTAT) and proportional to absolute temperature (PTAT) voltages
Implementation Method 2
A bandgap reference voltage circuit is designed using a combination of complementary to absolute temperature (CTAT) and proportional to absolute temperature (PTAT) voltages
Implementation Method 3
a differential error amplifier with negative feedback to minimize tolerance errors and ensure stability and accuracy
Data Source
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AI summary
Aspects of the disclosure are directed to generating a reference voltage with trim adjustment. Accordingly, a reference voltage with trim adjustment is generating which involves generating a trim current using at least one of a plurality of selectable parallel elements; inputting the trim current to parallel resistor branches to generate a first scaled voltage; and combining a first voltage with the first scaled voltage to generate the reference voltage.