Bandgap Reference Circuit Scaling Voltage Below 1.25V
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Solution Overview
Problem
Conventional bandgap reference circuits generate a reference voltage of approximately 1.25V, which is not suitable for recent IC designs requiring operation regions below this voltage, and they are not effectively immune to temperature variations.
Innovation Solution
A bandgap reference circuit comprising a PTAT circuit, a CATA circuit, and an output circuit that combine to generate a bandgap reference voltage by scaling both the PTAT and CATA voltages, allowing for a lower reference voltage output while maintaining temperature insensitivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a conventional bandgap reference circuit is used to generate a reference voltage, then the reference voltage is relatively insensitive to temperature variations, but the reference voltage level is fixed at approximately 1.25V which is not suitable for modern IC designs requiring lower voltage operation
Solution Approach 1:
The reference voltage generation is divided into two independent circuits: a first circuit generating a first reference voltage with temperature compensation, and a second circuit generating a second reference voltage. These are then combined through a voltage divider to achieve both temperature insensitivity and adjustable voltage levels.
Solution Approach 2:
A voltage divider circuit is introduced as an intermediary between the first and second reference voltage sources. This voltage divider enables flexible voltage level adjustment while preserving the temperature compensation characteristics of the first reference voltage circuit.
2Adaptability or versatility
If the reference voltage is reduced below 1.25V to meet modern IC design requirements, then voltage level adaptability is improved, but temperature stability becomes more difficult to maintain
Solution Approach 1:
The system separates temperature compensation functions (handled by the first circuit) from voltage level adjustment functions (handled by the second circuit and voltage divider). This segmentation allows the reference voltage to be scaled down while maintaining temperature stability through the dedicated compensation circuit.
Solution Approach 2:
The invention changes the voltage level parameter through the voltage divider ratio while maintaining the temperature compensation mechanism. By adjusting the voltage divider configuration, the output voltage can be scaled to any required level below 1.25V without compromising temperature stability.
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 proposed circuit effectively generates a reference voltage below 1.25V, addressing the need for lower voltage operation in IC designs and providing improved temperature stability by combining proportional-to-absolute-temperature and complementary-to-absolute-temperature voltage components.
Implementation Method 1
The first circuit and the second circuit complement each other for offsetting variations of the bandgap reference voltage due to temperature changes
Data Source
AI summary
A bandgap reference circuit includes a first circuit, a second circuit and a third circuit. The first circuit is for generating a first current and a first voltage according to a first reference voltage. The second circuit is coupled to the first circuit, for generating a second voltage according to the first voltage. The third circuit is coupled to the first circuit and the second circuit, for generating a voltage offset according to the first current, and generating a bandgap reference voltage according to the second voltage and the voltage offset. The first circuit and the second circuit complement each other for offsetting variations of the bandgap reference voltage due to temperature changes.