Bandgap Voltage Reference Using Time-Division Multiplexing
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Solution Overview
Problem
Existing bandgap voltage reference circuits are complex and require high gain bipolar transistors, which are not compatible with standard CMOS technologies, limiting their applicability and simplicity.
Innovation Solution
A single PN-junction device, such as a bipolar transistor, is used with different current magnitudes applied during different time periods to generate a temperature-compensated reversed bandgap voltage, simplifying the circuit structure and eliminating the need for multiple transistors, utilizing a capacitive voltage divider and amplifier for output staging.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional bandgap voltage reference circuits are used, then temperature independent reference voltage can be achieved, but the circuit complexity increases and high gain bipolar transistors are required
Solution Approach 1:
The patent applies periodic action by using two distinct time periods (first and second time periods) to sequentially charge and discharge capacitors in the capacitive voltage divider. During the first time period, current flows through the PN-junction to charge the capacitors, and during the second time period, the capacitors discharge to produce the output voltage. This time-division multiplexing approach eliminates the need for complex parallel circuit paths while maintaining temperature compensation, thereby reducing circuit complexity while preserving reliability.
2Reliability
If traditional bandgap voltage reference circuits are used, then reference voltage can be generated, but bipolar transistors with high gain are required which are not compatible with standard CMOS technologies
Solution Approach 1:
The patent changes the operating parameters by using a single PN-junction device operated in two different time periods with different current magnitudes, rather than using multiple bipolar transistors with high gain requirements. This parameter change from spatial configuration (multiple transistors) to temporal configuration (time-division) makes the circuit compatible with standard CMOS technologies while maintaining reference voltage generation capability.
3Reliability
If multiple transistors are used in bandgap reference circuit, then temperature compensation can be achieved, but the number of components and circuit complexity increases
Solution Approach 1:
The patent merges the functions of multiple transistors into a single PN-junction device by utilizing time-division multiplexing. The single device performs the role of multiple transistors by being operated in two different time periods with different current magnitudes, thereby achieving temperature compensation with fewer components and reduced circuit complexity.
Solution Approach 2:
The patent transitions from a spatial arrangement (multiple transistors connected in parallel) to a temporal arrangement (single device operated in time periods). This dimensional change from space to time allows temperature compensation to be achieved with a single PN-junction device, reducing the number of components while maintaining the temperature compensation function.
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 allows for a robust and less complex generation of reversed bandgap voltage references, compatible with low gain bipolar transistors, achieving temperature stability and precision without the complexity of prior art circuits.
Implementation Method 1
A current source selectively feeds a current of a first magnitude during a first period of time and a current of a second magnitude during a second period of time through the PN-junction. An output stage provides a voltage which is a combination of a first voltage drop across the PN-junction during the first period of time and a second voltage drop across the PN-junction during the second period of time.
Data Source
AI summary
An electronic device includes a bandgap reference voltage generation stage. The bandgap reference voltage generation stage comprises a device with a PN-junction, a current source feeding a first current during a first period of time and a second higher current during a second period of time through the PN-junction. The bandgap reference voltage is generated from a combination of a first voltage drop across the PN-junction during the first period of time and a second voltage drop across the PN-junction during the second period of time. This bandgap reference voltage is formed using switched capacitors.