Bandgap Reference Compensation for Radiation-Induced Base Currents
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Solution Overview
Problem
Conventional bandgap reference circuits do not account for the effects of total ionizing dose (TID) and intrinsic base currents, which can lead to shifts in bandgap reference voltage outputs and reduced reliability, especially in high radiation environments such as space.
Innovation Solution
The introduction of a compensation circuit that includes a compensation transistor and a compensation operational amplifier, which provides a compensation base current to the base terminal of the bipolar transistors in the bandgap reference circuit, effectively compensating for radiation-induced and intrinsic base currents.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional bandgap reference circuits are used, then the circuit design is simple, but the reliability deteriorates in high radiation environments due to TID and intrinsic base currents
Solution Approach 1:
The invention divides the bandgap reference circuit into multiple functional blocks: a conventional bandgap reference circuit block and a compensation circuit block. The compensation circuit is further segmented into compensation current sources, compensation transistors, and control logic. This segmentation allows the reliability improvement to be achieved through a modular addition rather than redesigning the entire circuit, thus managing complexity.
Solution Approach 2:
The invention introduces compensation transistors and compensation current sources as intermediary elements between the radiation-induced base currents and the bandgap reference output. These intermediary components capture and compensate for the harmful base currents before they affect the reference voltage, thereby improving reliability without directly modifying the core bandgap reference circuit.
2Reliability
If compensation circuits are added to account for radiation effects, then the reliability improves in high radiation environments, but the device complexity increases
Solution Approach 1:
The compensation circuit uses compensation transistors that are copies or replicas of the main bipolar transistors in the bandgap reference circuit. These compensation transistors are designed to match the electrical characteristics and radiation response of the main transistors, allowing them to accurately model and compensate for base current effects. This copying approach improves reliability while keeping the compensation circuit design systematic and manageable.
Solution Approach 2:
The invention implements feedback mechanisms where the compensation circuit continuously monitors the base currents of the main transistors and adjusts compensation currents accordingly. The control logic analyzes the operating conditions and dynamically adjusts the compensation to maintain accurate reference voltage despite radiation-induced variations, thereby improving reliability through adaptive correction.
3Stability of the object's composition
If the bandgap reference circuit compensates for temperature and power supply variations, then the temperature independence is improved, but the circuit does not account for radiation-induced base currents
Solution Approach 1:
The invention enhances the universality of the bandgap reference circuit by making it adaptable to multiple environmental conditions. The compensation circuit is designed to handle not only temperature and power supply variations (original functions) but also radiation-induced base current effects (new function). This multi-functionality allows the same circuit architecture to maintain stability across diverse operating conditions including high radiation environments.
Solution Approach 2:
The compensation circuit introduces dynamic adaptability to the otherwise static bandgap reference design. The control logic and compensation current sources can dynamically adjust their operation based on real-time conditions, including radiation levels, temperature, and power supply variations. This dynamic behavior enables the circuit to maintain temperature independence while simultaneously adapting to radiation effects that would otherwise degrade performance.
Data Source
AI summary
Systems, apparatuses, and methods that compensate for total ionizing doses and intrinsic base currents in transistors of a bandgap reference circuit are provided. A compensation circuit can include a compensation transistor with a size and one or more bias conditions that are based at least in part on a respective bipolar transistor of a bandgap reference circuit. The compensation circuit can include an operational amplifier that is configured to: (i) set a base-collector voltage of the compensation transistor to zero; and (ii) provide a compensation base current to a base terminal of the compensation transistor that is representative of at least a radiation-induced current transistor or an intrinsic base current for the respective bipolar transistor. A bandgap reference circuit can be augmented with one or more compensation circuits to accommodate for a total ionizing dose and/or an intrinsic base current for one or more transistors of the bandgap reference circuit.