On-Chip Resistor Correction Circuit for Precision Trim Without Laser
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Solution Overview
Problem
Integrated circuit resistors suffer from manufacturing process and environmental offsets, leading to precision issues beyond ±17%, which are not adequately addressed by existing laser trimming methods, resulting in high costs and inconsistent resistance values.
Innovation Solution
An on-chip resistor correction circuit utilizing a MOS transistor, operational amplifier, comparator, and controller to adjust resistance values by comparing with a reference voltage, employing a series of MOS transistors as switches to control resistor branches, ensuring resistance values align with a reference resistor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If laser trimming is used to correct resistor precision, then resistance accuracy can be improved, but manufacturing cost increases significantly
Solution Approach 1:
The patent replaces the mechanical laser trimming process with an electronic correction circuit implemented entirely on-chip. The correction circuit uses MOS transistors, operational amplifiers, and switches to electronically adjust resistance values, eliminating the need for external laser equipment and manual trimming operations. This substitution of mechanical/optical processing with electronic processing resolves the contradiction by maintaining high precision while dramatically reducing manufacturing cost and complexity.
Solution Approach 2:
The correction circuit is integrated directly onto the chip alongside the resistors, allowing the chip to self-correct its resistance values without requiring external intervention. The on-chip circuit automatically compensates for manufacturing variations through electronic adjustment, enabling the device to service its own precision requirements and eliminating costly post-fabrication trimming processes.
2Manufacturing precision
If laser trimming is applied during manufacturing, then resistance value can be adjusted, but offset due to working condition changes prevents obtaining desired values
Solution Approach 1:
The correction circuit employs dynamic electronic adjustment capabilities that allow real-time compensation for working condition changes. Unlike static laser trimming that sets a fixed resistance value, the electronic circuit can adaptively adjust resistance values in response to temperature, voltage, and other environmental variations, maintaining consistent performance throughout the device's operational lifecycle.
Solution Approach 2:
The correction circuit incorporates feedback mechanisms that continuously monitor actual resistance values and automatically adjust compensation parameters to maintain desired performance. This closed-loop control system detects deviations caused by working condition changes and applies corrective adjustments, ensuring reliable and consistent resistance values under varying operational conditions.
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
Achieves precise resistance correction by generating a temperature-independent current, mirroring it into internal resistors, and adjusting their values to match the reference resistor, thereby improving resistance accuracy and reducing environmental sensitivity.
Implementation Method 1
an operational amplifier (1) for performing operations on a reference voltage (Vref) and the voltage of the reference resistor (R1) to output the first control signal
Implementation Method 2
a comparator (2) for generating a comparison signal by comparing the voltage of the reference node (J1) and the reference voltage (Vref)
Implementation Method 3
a controller (4) for generating a control signal under the action of the comparison signal to control the branch where each of the remaining of plurality of resistors inside the chip (R0, R11, R12... R1N) is located to turn on or off
Data Source
Figure 1
AI summary
The invention discloses an on-chip resistor correction circuit, and belongs to the field of chip correction. The circuit comprises 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. The invention has the following beneficial effects: a reference resistor is provided outside of the chip, and a temperature-independent current is generated based on the reference voltage inside the chip; the generated current is mirrored into a resistor inside the chip, shunt resistance of an internal resistor is adjusted to make it infinitely close to the reference resistor.