Voltage Reference Using Single PN Junction and Digital Compensation
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Solution Overview
Problem
Existing voltage reference designs face challenges in achieving temperature stability without increasing costs, as they require large, precisely matched semiconductor devices to minimize temperature differences and manufacturing errors, which occupy valuable die space and are sensitive to temperature gradients.
Innovation Solution
A method using a single semiconductor device with two different currents passing through a PN diode, where the resulting voltages are stored and combined to create a temperature-independent reference voltage, allowing for small device sizes and low-cost manufacturing, and leveraging a microcontroller with an analog-to-digital converter to calculate precise current ratios and correct for temperature effects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If large, precisely matched semiconductor devices are used to minimize temperature differences and manufacturing errors, then temperature stability is improved, but die space is consumed and manufacturing cost increases
Solution Approach 1:
The patent combines the temperature sensing function and voltage reference function into a single integrated circuit structure. The temperature sensor utilizes the same PN junction as the voltage reference, allowing both functions to share the same physical structure and occupy the same die space, thereby eliminating the need for separate large matched devices.
Solution Approach 2:
The PN junction serves multiple functions simultaneously: it acts as both the voltage reference element and the temperature sensor. By making the temperature sensor universal to the voltage reference structure, the patent eliminates the need for dedicated separate components, reducing die space while maintaining temperature stability.
2Stability of the object's composition
If large, precisely matched semiconductor devices are used to minimize temperature differences and manufacturing errors, then temperature stability is improved, but manufacturing cost increases
Solution Approach 1:
The patent combines the temperature sensing function and voltage reference function into a single integrated circuit structure. The temperature sensor utilizes the same PN junction as the voltage reference, allowing both functions to share the same physical structure and occupy the same die space, thereby eliminating the need for separate large matched devices.
Solution Approach 2:
The voltage reference circuit itself provides the temperature sensing capability through its inherent PN junction characteristics. The circuit uses its own operating currents and voltages to generate the temperature-dependent signals, eliminating the need for separate dedicated temperature sensor components and reducing manufacturing complexity.
3Measurement precision
If separate temperature sensor and voltage reference circuits are used, then temperature measurement capability is improved, but device complexity increases
Solution Approach 1:
The patent combines the temperature sensing function and voltage reference function into a single integrated circuit structure. The temperature sensor utilizes the same PN junction as the voltage reference, allowing both functions to share the same physical structure and occupy the same die space, thereby eliminating the need for separate large matched devices.
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
This approach enables a precise, low-power, and cost-effective voltage reference with improved temperature stability, reducing the need for large components and allowing digital compensation for temperature variations, thus enhancing system accuracy without the drawbacks of prior art.
Implementation Method 1
the utilization of semiconductor diodes (or bipolar transistors), which are behaving according to the 'classic' Shockley diode equation shown in FIG. 4(a). An approximate relationship may be derived from the Shockley diode equation: V1−V2=ΔVd=(nk/q)*T*In(J1/J2)
Implementation Method 2
the forward voltage of the diode has CTAT characteristics due to temperature dependency of the quantity Is in the Shockley diode equation
Data Source
AI summary
A highly accurate voltage reference and temperature sensor circuit requires only several low-cost components in addition to a general-purpose microcontroller with an analog-to-digital converter. Unlike known circuits, the circuit disclosed does not rely on matching between a pair of semiconductor devices, as only a single semiconductor junction is used. All of the signal processing may be performed digitally.