Voltage Reference Circuit Layout for Contact-Resistant Stability
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Voltage reference circuits face challenges in maintaining a constant output voltage due to variations in contact resistance, which can be critical in safety-critical applications like lithium ion batteries where stability over years is required.
Innovation Solution
A voltage reference circuit design utilizing a resistive track with strategically placed sense and force contacts, where resistors are defined by the length of the track rather than contact pads, and a counter-bias voltage mechanism to counteract temperature-dependent voltage biases, ensuring the output voltage is independent of temperature and contact resistance variations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If contact resistance variations occur in conventional voltage reference circuits, then the output voltage stability deteriorates, but using traditional resistor configurations increases sensitivity to contact resistance changes
Solution Approach 1:
The patent introduces sense contacts as intermediary elements between the force contacts and the resistive track. These sense contacts measure the voltage at specific points along the resistive track without drawing significant current, thereby eliminating the impact of contact resistance variations on the reference voltage output. The sense contacts act as mediators that isolate the measurement function from the current-carrying function.
Solution Approach 2:
The patent segments the resistive track into multiple portions with different resistance values (first resistor, second resistor, third resistor) along a single continuous track. This segmentation allows the circuit to use voltage division ratios that are independent of the absolute contact resistance values at the force contacts, as the contact resistance affects all segments equally and cancels out in the ratio calculation.
2Reliability
If temperature variations occur, then the voltage bias of the P-N junction changes, but maintaining a constant reference voltage requires additional compensation mechanisms
Solution Approach 1:
The patent utilizes the temperature-dependent characteristics of the P-N junction by applying a voltage bias that causes the junction to conduct current. The P-N junction's forward voltage drop changes predictably with temperature, and this change is exploited to generate a compensation voltage that counteracts the temperature drift of the reference voltage output, thereby stabilizing the overall reference voltage across temperature variations.
Solution Approach 2:
The patent converts the harmful temperature-dependent voltage drift of the P-N junction into a beneficial compensation mechanism. By deliberately biasing the P-N junction and utilizing its temperature-sensitive characteristics, the circuit generates a compensating voltage signal that offsets the temperature-induced errors in the reference voltage, thereby transforming a source of error into a correction mechanism.
3Reliability
If a single resistive track is used to define multiple resistors, then contact resistance variations are minimized, but the circuit layout becomes more constrained
Solution Approach 1:
The patent merges multiple resistor functions into a single continuous resistive track. Instead of using separate discrete resistors with multiple contact points, the invention implements all required resistance values (first resistor, second resistor, third resistor) as segments of one unified resistive element. This merging eliminates the need for multiple independent contact connections, thereby reducing the impact of contact resistance variations on the circuit's reference voltage output.
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
This design significantly reduces errors associated with contact resistance variations, providing a stable and reliable constant voltage reference, essential for long-term applications in safety-critical systems.
Implementation Method 1
the first component arrangement comprises a P-N junction which has a temperature dependent voltage bias
Implementation Method 2
a first portion of the resistive track comprising the length between the first sense contact and the second sense contact defines a first resistor and a second portion of the resistive track comprising the length between the third sense contact and the closest of the first sense contact and the second sense contact to the third sense contact defines a second resistor
Data Source
Figure 1~2
Figure 3~4
Figure 5~6
AI summary
A voltage reference circuit comprising: a resistive track having a first force contact and a second force contact, the first and second force contacts configured to pass a current through the resistive track; a first sense contact, a second sense contact and a third sense contact wherein each of the sense contacts are arranged at different positions along the resistive track between the first and second force contacts and the sense contacts arranged to define a first resistor and a second resistor; a first component arrangement comprising a P-N junction which has a temperature dependent voltage bias; a second component arrangement; wherein one or both of the first component arrangement and the second component arrangement provide for a counter-bias voltage, the counter bias voltage for countering the temperature dependent voltage bias of the P-N junction such that the voltage reference circuit is configured to provide a constant output reference voltage.