Voltage Reference Trim Circuit for Low-Leakage Accuracy Control
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Solution Overview
Problem
High precision voltage reference integrated circuits face challenges in maintaining accuracy and low quiescent current, especially in battery-powered applications, where existing trimming methods can introduce errors due to resistance variations and leakage currents.
Innovation Solution
A voltage reference circuit with a binary weighted current flow control circuit that adjusts the voltage by controlling the current through a resistor, using a combination of transistors and switches to minimize errors and reduce quiescent current, incorporating a resistor ladder or one hot switch control for precise voltage trimming.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional trimming methods are used to adjust voltage reference accuracy, then voltage accuracy can be improved, but resistance variations and leakage currents introduce errors that worsen precision
Solution Approach 1:
The patent replaces traditional mechanical trimming methods with a digital control system. A microcontroller or logic circuit generates control signals that switch between multiple resistor elements in a binary-weighted array, eliminating mechanical contact and associated resistance variations. The trimming is achieved through electronic switching rather than physical adjustment, thereby reducing trimming errors.
Solution Approach 2:
The patent introduces an intermediary control circuit that mediates between the voltage reference generator and the trimming mechanism. This intermediary layer processes trimming commands and controls the switching of resistor elements, isolating the sensitive voltage reference from direct mechanical or manual trimming operations that could introduce errors.
2Measurement precision
If high precision trimming components are added to improve voltage accuracy, then measurement precision improves, but device complexity increases
Solution Approach 1:
The trimming mechanism is segmented into multiple discrete resistor elements arranged in a binary-weighted array. Each element can be independently controlled by switching circuits, allowing precise voltage adjustment through digital control. This segmentation enables high precision trimming while maintaining modular circuit architecture that manages complexity.
Solution Approach 2:
The patent changes the trimming parameter from continuous mechanical adjustment to discrete digital control. By using a binary-weighted resistor array controlled by digital switches, the trimming operation transitions from an analog mechanical process to a digital selection process, improving precision while simplifying control logic.
3Use of energy by moving object
If low quiescent current is maintained for battery-powered applications, then energy consumption is reduced, but voltage reference accuracy becomes more difficult to maintain
Solution Approach 1:
The patent implements periodic calibration or self-test routines that can be executed at low current levels. The voltage reference circuit includes built-in trimming capability that can be activated periodically to maintain accuracy without requiring continuous high current operation. This periodic action allows the system to maintain low quiescent current while preserving voltage reference accuracy through occasional calibration.
4Device complexity
If traditional voltage reference circuits are used, then device simplicity is maintained, but accuracy and low quiescent current requirements cannot be simultaneously met
Solution Approach 1:
The patent merges the voltage reference generation function with the trimming control function into a single integrated circuit. The binary-weighted resistor array and switching circuits are integrated with the voltage reference generator, allowing both functions to coexist in a unified architecture. This merging enables high precision and low current operation without requiring separate external trimming components.
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 achieves high accuracy and low quiescent current, effectively addressing the limitations of traditional trimming methods by minimizing resistance errors and leakage currents, ensuring stable voltage references across varying conditions.
Implementation Method 1
A voltage at the reference output is adjusted by controlling a current through a resistor that is coupled to the reference output
Implementation Method 2
A voltage reference circuit with a binary weighted current flow control circuit that adjusts the voltage by controlling the current through a resistor, using a combination of transistors and switches
Data Source
AI summary
Described embodiments include a circuit for controlling a voltage drop. The circuit includes a resistor coupled between an output voltage terminal and a reference voltage terminal. First, second and third switches each have respective first, second and third switch terminals. The respective second switch terminals are connected together and are coupled to the output voltage terminal. The respective third switch terminals are connected together and are coupled to the reference voltage terminal. A first transistor is coupled between a supply voltage terminal and the first switch. A second transistor is coupled between the supply voltage terminal and the second switch. A third transistor is coupled between the supply voltage terminal and the third switch. Control terminals of the first, second and third transistors are coupled to a gate control terminal.