On-Chip Port Current Control via Resistor Ratio
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Solution Overview
Problem
Existing current control circuits in electronic chips face challenges in accurately measuring and controlling current using on-chip resistors due to large tolerance in resistance values, requiring expensive trimming or calibration, and necessitate additional pins and external connections.
Innovation Solution
An on-chip sense resistor and reference resistor with a predetermined relationship are used, along with a reference current source, differential amplifier, and an electronically controlled switch to accurately control and measure current, eliminating the need for precise resistor values and external connections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If an external sense resistor is used to measure current, then current measurement accuracy is improved, but the number of external connections and cost increase
Solution Approach 1:
The patent combines the sense resistor with the integrated circuit chip by fabricating it as an on-chip resistor using standard semiconductor manufacturing processes. This eliminates the need for external sense resistors and external connections, while maintaining current measurement functionality within the chip structure.
Solution Approach 2:
The patent extracts the sense resistor from the external domain and integrates it directly onto the chip, removing the need for external components and connections while preserving the current measurement function.
2Device complexity
If an on-chip sense resistor is used, then external connections are reduced, but resistance value tolerance increases making accurate measurement difficult
Solution Approach 1:
The patent changes the approach from relying on absolute resistance value precision to relying on resistance ratio precision. By using a ratio meter to measure the ratio between the sense resistor and a reference resistor, the system achieves accurate current measurement despite large absolute tolerance in individual resistor values.
Solution Approach 2:
The patent introduces a reference resistor and a ratio meter as intermediary elements. The reference resistor serves as a comparison standard, and the ratio meter measures the ratio between the sense resistor and reference resistor, enabling accurate current measurement without requiring precise absolute resistance values.
3Measurement precision
If expensive trimming or calibration is performed, then current measurement accuracy is improved, but cost increases
Solution Approach 1:
The patent enables the system to self-measure and self-calibrate by using the ratio meter to continuously monitor the ratio between the sense resistor and reference resistor. This eliminates the need for expensive external trimming or calibration equipment, as the system performs its own calibration using integrated 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
This solution allows for accurate current control and measurement within the chip without expensive calibration, reducing costs and complexity while maintaining temperature independence.
Implementation Method 1
a sense voltage is produced across the on-chip sense resistor responsive to a port current flowing through the on-chip sense resistor
Implementation Method 2
A reference current source of a predetermined value is generated, the generated reference current arranged to flow through an on-chip reference resistor thereby producing a reference voltage thereacross
Data Source
AI summary
A port current control arrangement, constituted of: a current source arranged to generate a reference current or a predetermined value; an on-chip reference resistor, the generated reference current arranged to produce a reference voltage across the on-chip reference resistor; an on-chip sense resistor, a port current arranged to flow through the on-chip sense resistor and produce a sense voltage across the on-chip sense resistor, wherein the resistance of the on-chip sense resistor exhibits a predetermined relationship with the resistance of the first on-chip reference resistor; and a current control circuit, a first input of the current control circuit arranged to receive the produced reference voltage and a second input of the current control circuit arranged to receive the sense voltage, wherein the current control circuit is arranged to limit the port current to a value responsive to the received reference voltage and the received sense voltage.