On-Chip Resistor Correction Circuit for Precision Matching
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Solution Overview
Problem
Integrated circuit resistors are prone to manufacturing process and environmental offsets, leading to insufficient precision, especially in high-speed and high-frequency applications, where existing correction methods like laser trimming are costly and unreliable.
Innovation Solution
An on-chip resistor correction circuit comprising MOS transistors, operational amplifiers, comparators, and controllers that use a reference resistor and dichotomic control to adjust internal resistor values, ensuring precise resistance matching by generating a temperature-independent current and mirroring it within the chip.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If laser trimming is used to correct resistor values, then manufacturing precision is improved, but device complexity and cost increase
Solution Approach 1:
The patent replaces the mechanical laser trimming process with an electronic correction circuit implemented entirely in software/firmware. The correction circuit uses digital signal processing to compensate for resistor variations, eliminating the need for physical laser trimming equipment and complex mechanical adjustment mechanisms.
Solution Approach 2:
The patent creates a digital model or lookup table that maps measured resistor values to correction factors. Instead of physically adjusting each resistor, the system copies the correction strategy through software algorithms that calculate and apply compensation values based on pre-characterized resistor behavior patterns.
2Manufacturing precision
If laser trimming is used to correct resistor values, then manufacturing precision is improved, but reliability deteriorates due to offset during trimming
Solution Approach 1:
The correction circuit performs self-calibration by automatically measuring its own resistor values and applying corrections without external intervention. The system uses internal reference voltages and ADC measurements to autonomously determine and compensate for resistor offsets, eliminating reliance on external laser trimming processes that introduce instability.
Solution Approach 2:
The patent implements a feedback mechanism where the correction circuit continuously monitors resistor values through ADC measurements and dynamically adjusts correction factors. This closed-loop feedback ensures that any drift or offset is automatically compensated, maintaining stable and reliable resistor values throughout operation.
3Measurement precision
If multiple correction measurements are performed, then measurement precision is improved, but loss of time increases
Solution Approach 1:
The patent performs preliminary characterization of resistor values during manufacturing or initial startup, storing correction factors in lookup tables or memory. This preliminary action allows the system to quickly apply pre-calculated corrections during operation without performing time-consuming measurements and calculations in real-time.
Solution Approach 2:
The system performs a limited number of measurements (e.g., 3-5 samples) rather than exhaustive testing, using statistical methods to achieve sufficient precision. This partial action approach achieves acceptable measurement accuracy while significantly reducing the time required compared to extensive multi-point characterization.
Data Source
AI summary
An on-chip resistor correction circuit includes a first MOS transistor connected between VDD and a reference resistor, the other end of the reference resistor being grounded; an operational amplifier for outputting a first control signal based on a reference voltage and a voltage of the reference resistor; a second MOS transistor connected between VDD and a reference node; a branch where each of the on-chip resistors is located is controllably connected between the reference node and ground; a comparator for generating a comparison signal based on the voltage of the reference node and the reference voltage; and a controller for generating a control signal under the action of the comparison signal to control the branch where each of the on-chip resistors is located to turn on or off.