Reference Current Source Using External Resistor and Current Mirror
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Solution Overview
Problem
Integrated circuits face challenges in generating exact reference currents due to production-related fluctuations in resistors, requiring external resistors that add space and cost, and existing solutions struggle to generate stable reference voltages and currents without additional connection terminals.
Innovation Solution
A circuit with a current mirror arrangement and measurement and evaluation circuit that uses a programming resistor to generate a reference current, eliminating the need for an additional connection terminal by integrating the resistor within the circuit and using a bandgap reference voltage source to maintain stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If an external resistor is used to generate a reference current, then the reference current can be generated with small production-related fluctuations, but an additional connection terminal is required which increases space requirement and costs
Solution Approach 1:
The patent combines the reference current generation function with the existing output terminal by using a current mirror arrangement. The external resistor is connected to the output terminal, and the current mirror copies the output current to generate a stable reference current without requiring additional connection terminals. This merging of functions eliminates the need for separate reference current terminals while maintaining manufacturing precision.
Solution Approach 2:
The output terminal is given multiple functions: it serves both as the output terminal for the programmable circuit and as the connection point for generating the reference current. By making the terminal universal, the patent eliminates the need for additional dedicated reference current terminals, reducing space requirements while maintaining the stability benefits of external resistors.
2Manufacturing precision
If a nonreactive resistor with exact resistance value is produced in integrated circuits, then the reference current can be generated exactly, but the production complexity increases significantly
Solution Approach 1:
The patent extracts the high-precision resistor from the integrated circuit fabrication process and places it externally. By taking out the resistor requirement from the complex IC production process, the patent achieves exact resistance values without increasing production complexity. The external resistor can be selected with precise tolerance values without affecting the standard IC manufacturing process.
3Stability of the object's composition
If a reference voltage is applied across an external resistor to generate reference current, then the reference current stability is improved, but the circuit requires additional connection terminals
Solution Approach 1:
The patent merges the reference current generation path with the existing output current path using a current mirror arrangement. The same external resistor and reference voltage that generate the output current also generate the reference current through the current mirror, eliminating the need for separate connection terminals while maintaining reference current stability.
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 precise generation of reference currents with minimal production-related fluctuations, reducing space and cost requirements while maintaining circuit stability and programmability through the use of discrete resistors with small fluctuations.
Implementation Method 1
A circuit which can be programmed using a resistor and has a reference current source... The current mirror arrangement is coupled to an output current path containing the output terminal and provides a reference current which is dependent on the output current and the control signal
Implementation Method 2
An exact reference voltage can be generated in integrated circuits using a bandgap circuit, for example
Data Source
AI summary
A circuit configured to be programmed using a resistor includes an output terminal, a reference voltage source, a first circuit, and a current mirror arrangement. The output terminal is configured to be connected to a programming resistor. The reference voltage source is configured to generate a reference voltage on the output terminal. The measurement and evaluation circuit is configured to detect an output current on the output terminal, and to generate a control signal which is dependent on the output current. The current mirror arrangement is coupled to an output current path containing the output terminal and provides a reference current which is dependent on the output current and the control signal.