Bandgap Reference Voltage Circuitry with Segmented BJT Branches
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Solution Overview
Problem
Conventional bandgap reference voltage generators require high area cost and part-to-part calibration, leading to accuracy issues and increased test costs.
Innovation Solution
The integration of bipolar junction transistors (BJTs) in a compact circuit arrangement with a resistance ratio-based bandgap reference voltage circuitry, utilizing a network of switches and resistors controlled by a finite state machine, and current-providing circuitry for accurate bias currents and voltages, which minimizes sensitivity to error sources like BJT base current mismatch and MOSFET device mismatch.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional bandgap reference voltage generators use high area cost and part-to-part calibration, then accuracy is improved, but device area and test cost increase
Solution Approach 1:
The circuit is divided into two separate closed-loop branches, each with its own amplifier and BJT configuration. This segmentation allows independent optimization of each branch while achieving overall high accuracy without requiring large device area or calibration procedures.
Solution Approach 2:
A resistance ratio mechanism is introduced as an intermediary element that cancels out process variations and error sources. The ratio of resistors in the two branches serves as a mediator that eliminates the need for calibration while maintaining high accuracy with minimal area.
2Measurement precision
If conventional bandgap reference voltage generators use high area cost and part-to-part calibration, then accuracy is improved, but test cost increases
Solution Approach 1:
The circuit performs self-calibration through its inherent resistance ratio mechanism. The two closed-loop branches automatically compensate for process variations and error sources without requiring external calibration equipment or procedures, thereby eliminating test costs while maintaining high accuracy.
Solution Approach 2:
The circuit utilizes parameter changes in the resistance ratios to compensate for process variations. By designing the resistance network such that ratios remain stable across process variations, the circuit achieves high accuracy without requiring calibration tests.
3Measurement precision
If the circuit minimizes sensitivity to error sources like BJT base current mismatch and MOSFET device mismatch, then accuracy is improved, but circuit complexity increases
Solution Approach 1:
The error sources such as BJT base current mismatch and MOSFET device mismatch are extracted and cancelled out through the resistance ratio mechanism. The circuit configuration removes these error terms from the transfer function, achieving high accuracy without adding complex compensation circuits.
4Stability of the object's composition
If the circuit maintains accuracy across changing temperatures, then temperature stability is improved, but circuit design complexity increases
Solution Approach 1:
The circuit exploits parameter changes in semiconductor devices with temperature. The resistance ratio mechanism is designed to automatically compensate for temperature-dependent variations in BJT and MOSFET parameters, maintaining accuracy across temperature ranges without requiring complex temperature compensation circuits.
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 solution achieves accurate bandgap reference voltage generation with low area cost and without calibration, maintaining accuracy across changing temperatures and reducing sensitivity to error sources, while allowing for single-temperature calibration for higher accuracy.
Implementation Method 1
The bandgap reference voltage circuitry utilizes bipolar junction transistors (BJTs) to generate temperature-related signals that are combined into a bandgap reference voltage that is constant over changing temperatures
Implementation Method 2
The resistance ratio may be implemented by a resistor divider, part of which may be implemented using a network of switches and resistors
Data Source
AI summary
An embodiment for bandgap reference voltage circuitry includes: a bandgap reference voltage generator including: a first bipolar junction transistor (BJT); a first amplifier having a non-inverting input coupled to a collector of the first BJT and a first output node configured to provide a bandgap reference voltage; a first resistor coupled between a base of the first BJT and the first output node; a second BJT; a second amplifier having a non-inverting input coupled to a collector of the second BJT and a second output node coupled to a junction node; a second resistor coupled between a base of the second BJT and the junction node; and a third resistor coupled between the base of the first BJT and the junction node.