Op Amp Offset Voltage Temperature Coefficient Adjustment
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Solution Overview
Problem
Differential operational amplifiers suffer from input offset voltage errors due to transistor and resistor mismatches, which are amplified and vary with temperature, causing errors in signal amplification.
Innovation Solution
Implementing current sources with positive and negative temperature coefficients to generate additional offset voltage coefficients that compensate for the initial offset voltage temperature coefficient, thereby maintaining a constant error over a range of temperatures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If current sources with positive and negative temperature coefficients are implemented to compensate offset voltage temperature coefficient, then temperature stability of offset voltage is improved, but device complexity increases
Solution Approach 1:
The patent applies parameter changes by utilizing current sources with opposite temperature coefficients (one positive, one negative) to dynamically adjust and compensate for the offset voltage temperature coefficient. By changing the temperature dependence parameters of the current sources, the system achieves temperature stability without requiring complex structural modifications to the differential amplifier core.
2Manufacturing precision
If transistor and resistor matching is improved to reduce input offset voltage, then manufacturing precision is improved, but fabrication complexity and cost increase
Solution Approach 1:
The patent converts the harmful effect of temperature variation on offset voltage into a beneficial compensation mechanism. By intentionally introducing current sources with opposite temperature coefficients, the system uses temperature dependence itself to cancel out temperature-induced offset errors, transforming a manufacturing limitation into a functional solution.
3Measurement precision
If offset voltage error is reduced through better component matching, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent introduces current sources as intermediary elements that mediate between the differential amplifier and the temperature environment. These current sources act as a buffer that actively compensates for temperature effects, allowing the core amplifier to maintain high measurement precision without requiring extremely tight component matching.
Data Source
AI summary
An offset voltage temperature coefficient reduction system for a differential operational amplifier is disclosed. In one embodiment, the offset voltage temperature coefficient reduction system comprises a first current source generating a first current with a positive temperature coefficient and a second current source generating a second current with a negative temperature coefficient, where the first current source and the second current source are coupled to their respective output nodes of the differential op amp such that an error due to an input offset voltage of the differential operational amplifier is approximately constant over a range of temperature, and where a difference between the first current and the second current is approximately zero at a reference temperature. In similar manner, the offset voltage temperature coefficient can be also adjusted to desired value other than zero.