Reference Current Source With Temperature-Coefficient Matching
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Solution Overview
Problem
Existing reference current sources struggle to output a fixed current value that is not affected by temperature variations, necessitating additional resistors to suppress temperature characteristics, which increases circuit size and may compromise precision.
Innovation Solution
A reference current source is designed with a first and second semiconductor element, a conversion resistor, and an amplifier, utilizing a current mirror circuit to cancel out temperature characteristics by matching the temperature coefficients of the differential voltage and resistor, thereby reducing the need for additional resistors and maintaining precision.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If additional resistors are added to suppress temperature characteristics, then temperature stability is improved, but circuit size increases and precision may be compromised
Solution Approach 1:
The patent utilizes the temperature coefficient parameter of the resistor to match the temperature characteristic of the differential voltage. By selecting a resistor with a specific temperature coefficient that corresponds to the temperature characteristic of the differential voltage between semiconductor elements, the temperature dependence of the reference current is compensated without requiring additional temperature stabilization components.
Solution Approach 2:
The patent employs a current mirror circuit to copy and replicate the compensated current characteristics. The current mirror circuit replicates the current flowing through the semiconductor elements and resistor combination, providing a stable reference current that maintains the temperature compensation characteristics while avoiding the need for separate temperature stabilization circuitry.
2Temperature
If additional resistors are added to suppress temperature characteristics, then temperature stability is improved, but manufacturing precision requirements increase
Solution Approach 1:
The patent changes the approach from using multiple resistors with individually controlled precision to using a single resistor whose temperature coefficient parameter is matched to the differential voltage characteristics. This parameter matching approach reduces the cumulative precision requirements compared to using multiple high-precision resistors in traditional temperature compensation circuits.
Solution Approach 2:
The patent merges the temperature compensation function into the existing current generation circuitry by incorporating a single resistor with matched temperature characteristics. This consolidation eliminates the need for separate precision resistors dedicated solely to temperature compensation, thereby reducing overall manufacturing precision requirements while maintaining temperature stability.
3Device complexity
If circuit size is reduced by removing additional resistors, then device complexity is reduced, but temperature stability may worsen
Solution Approach 1:
The patent achieves temperature stability without additional resistors by changing the parameter selection of the existing resistor. By choosing a resistor with a temperature coefficient that matches the differential voltage temperature characteristic, the circuit maintains temperature compensation functionality while keeping the component count low and circuit size reduced.
Solution Approach 2:
The current mirror circuit copies the temperature-compensated current characteristics from the main current path, allowing the compensated reference current to be generated without requiring separate temperature stabilization components. This copying mechanism preserves temperature stability while minimizing circuit size.
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 effectively suppresses temperature effects on the reference current, enhancing precision while minimizing circuit size, and reducing sensitivity to stress-induced fluctuations.
Implementation Method 1
The conversion resistor converts forward voltages of the first semiconductor element and the second semiconductor element into a converted current, or converts a differential voltage into a converted current
Implementation Method 2
an amplifier, wherein the first semiconductor element is connected between a first input terminal of the amplifier and a ground, the second semiconductor element and the conversion resistor are connected in series between a second input terminal of the amplifier and the ground
Implementation Method 3
a current mirror circuit, wherein the current mirror circuit controls an output current of the amplifier, and outputs a reference current corresponding to the converted current
Data Source
AI summary
A reference current source includes first and second semiconductor elements, a conversion resistor, an amplifier, and a current mirror circuit. The first semiconductor element includes a single diode or a single transistor, and the second semiconductor element includes diodes or transistors connected in parallel. The conversion resistor converts forward voltages of the first and second semiconductor elements or a differential voltage between the first and second semiconductor elements into a converted current. The amplifier has first and second input terminals. The first semiconductor element is connected between the first input terminal and a ground, and the second semiconductor element and the conversion resistor is connected between the second input terminal and the ground. The current mirror circuit outputs a reference current corresponding to the converted current. The conversion resistor has a temperature coefficient being on a level with a temperature coefficient of the differential voltage.