Voltage Reference Circuit Temperature Compensation
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Solution Overview
Problem
Conventional voltage reference circuits have a non-zero temperature coefficient due to their dependence on absolute temperature (T) and T ln(T), leading to significant variations in reference voltage over temperature ranges, which cannot be fully eliminated.
Innovation Solution
A voltage reference circuit with temperature compensation, comprising positive and negative temperature coefficient generating units, a temperature compensation circuit, a mirror circuit, and a voltage divider, which specifically compensates for T and T ln(T) terms to produce a reference voltage with zero temperature coefficient, allowing for adjustable output voltage values.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional voltage reference circuit uses weighted summing of PN junction voltages to generate reference voltage, then the circuit can provide a stable reference voltage, but the temperature coefficient cannot be fully eliminated due to dependence on T and T ln(T)
Solution Approach 1:
The patent segments the temperature compensation function into two independent units: a positive temperature coefficient generating unit that generates voltages with T ln(T) characteristics, and a negative temperature coefficient generating unit that generates voltages with T characteristics. This segmentation allows each unit to specifically target and compensate for particular temperature-dependent terms, enabling complete elimination of the temperature coefficient while maintaining reference voltage stability.
2Manufacturing precision
If voltage reference circuit uses standard process technology with temperature compensation, then temperature coefficient is reduced to 40 ppm/°C, but cannot achieve zero temperature coefficient due to inherent T and T ln(T) dependence
Solution Approach 1:
The patent changes the parameter characteristics of the temperature compensation by using two distinct generating units with different temperature coefficient signs. The positive temperature coefficient generating unit produces voltages proportional to T ln(T), while the negative temperature coefficient generating unit produces voltages proportional to T. By adjusting the weighting factors in the summing circuit, the patent achieves complete cancellation of temperature-dependent terms, transforming the compensation from partial (40 ppm/°C) to complete (zero temperature coefficient).
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
The circuit achieves a zero-temperature coefficient reference voltage, eliminating variations associated with T and T ln(T), and offers flexible output voltage adjustment within a certain range, enhancing precision and adaptability compared to conventional designs.
Implementation Method 1
The positive temperature coefficient generating unit generates a positive temperature coefficient voltage with item T ln (T)... ΔVBEQ10,Q20 is related to T, and VBEQ10 is not only relevant to T, but also to T ln(T)
Implementation Method 2
The negative temperature coefficient generating unit generates positive temperature coefficient voltage with both Items T and T ln (T)... VBEQ10 is not only relevant to T, but also to T ln(T)
Implementation Method 3
The circuit generates low temperature coefficient voltage by weighted summing of positive and negative temperature coefficient voltages to reduce variation of the reference voltage with temperature
Data Source
AI summary
The present invention pertains to a voltage reference circuit based on temperature compensation, comprising positive and negative temperature coefficient generating units, temperature compensation circuit, image circuit and voltage divider. In this circuit, Item T is compensated with Item T, and Item T ln(T) is compensated by Item T in (T), which features a well-targeted compensation performance. The circuit outputs a reference voltage with zero temperature coefficient, which is independent to T and T ln (T). The output voltage value could be defined by adjusting the ratio of resistance in voltage divider. The invention provides a voltage reference circuit featuring good compensation, zero temperature coefficient and adjustable output voltage. The invention has a better compensation than the conventional one and a fixed output voltage, and it totally eliminates the temperature coefficient. The invention has wide application in analog IC and digital/analog mixed IC.