On-Chip Reference Current Calibration for Temperature Stability
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Solution Overview
Problem
Conventional reference current generating circuits require external test machines for calibration, increasing manufacturing and packaging costs due to the need for output pads, and face challenges with high accuracy requirements for small currents.
Innovation Solution
A reference current generating circuit with an automatic calibration mechanism using a temperature sensing circuit, adjustable resistor, current mirror, and calibration circuit to determine optimal resistance values without external components, ensuring stable reference currents across temperature variations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If external test machines and output pads are used for calibration, then calibration accuracy can be achieved, but manufacturing costs and packaging difficulty increase
Solution Approach 1:
The patent extracts the calibration function from external test machines and implements it internally using an on-chip calibration circuit. This removes the need for external pads and test equipment, thereby reducing manufacturing costs while maintaining calibration accuracy through internal automated measurement and adjustment mechanisms
Solution Approach 2:
The calibration circuit performs self-calibration using internal components including voltage references, current sources, and digital-to-analog converters. The system automatically measures and adjusts its own parameters without external intervention, eliminating the need for external test machines and reducing manufacturing complexity
2Measurement precision
If external test machines are used for calibration, then current measurement can be performed, but test machine accuracy requirements and additional costs increase
Solution Approach 1:
The patent merges the calibration measurement function with the reference current generation circuit by integrating voltage references, current sources, and measurement circuits on the same chip. This consolidation eliminates the need for separate external test machines, reducing both equipment complexity and measurement accuracy requirements while maintaining calibration precision
3Ease of operation
If output pads are added for calibration, then external calibration is enabled, but packaging difficulty increases
Solution Approach 1:
The patent removes the need for external output pads by extracting the calibration measurement function into the internal circuit. The calibration process is completely internalized, using on-chip components to measure and adjust reference current parameters, thereby eliminating packaging complexity associated with external pads while maintaining full calibration functionality
Data Source
AI summary
A reference current generating circuit includes a temperature sensing circuit, an adjustable resistor, a current mirror, and a calibration circuit. The temperature sensing circuit senses a temperature of the reference current generating circuit to provide a voltage. The adjustable resistor generates a reference current according to the voltage. The current mirror generates an output current according to the reference current. The calibration circuit includes a resistor, a comparator and a control circuit. The resistor generates an output voltage according to the output current. The comparator compares the output voltage with a reference voltage to generate a comparison result. The control circuit sequentially generates and transmits multiple control signals to the adjustable resistor, and determines a final control signal according to the comparison result.