Fractional Bandgap Circuit for Low-Voltage Reference Stability
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Solution Overview
Problem
Existing bandgap reference circuits face challenges in achieving low power consumption and small size while maintaining efficiency, as designs with less than 1.8V supply require complex three p-n junction configurations, increasing cost and complexity.
Innovation Solution
A fractional bandgap circuit using two p-n junctions with PTAT and CTAT servo loops, combined with a resistor, generates a temperature-independent reference voltage, incorporating a gain-boost technique and start-up circuit for stable operation at low supply voltages, and employing a U-shaped resistor layout for compact design.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If a bandgap reference circuit uses three p-n junctions to achieve low power consumption and low supply voltage operation, then power consumption and supply voltage are reduced, but device complexity and manufacturing cost increase
Solution Approach 1:
The patent extracts and eliminates one p-n junction from the traditional three-junction bandgap reference circuit, reducing the configuration to two p-n junctions. This extraction maintains the low power consumption and low supply voltage operation while removing the unnecessary complexity associated with the third junction, thereby resolving the contradiction between power efficiency and circuit complexity
Solution Approach 2:
The patent changes the operating parameters of the bandgap reference circuit by optimizing the supply voltage to operate below 1.8V and adjusting the current densities in the two p-n junctions. These parameter changes enable low power consumption without requiring the complex three-junction configuration, thus resolving the contradiction between power usage and device complexity
2Use of energy by moving object
If a bandgap reference circuit uses three p-n junctions to achieve low power consumption, then power usage is reduced, but manufacturing cost increases
Solution Approach 1:
By extracting and removing one p-n junction from the circuit configuration, the patent simplifies the manufacturing process. The two-junction design requires fewer fabrication steps and less complex process control compared to three-junction designs, thereby reducing manufacturing cost while maintaining low power usage through optimized operation of the remaining junctions
Solution Approach 2:
The patent employs a simpler two-junction configuration that is cheaper to manufacture using standard CMOS processes. The reduced complexity of the circuit allows for more economical fabrication with fewer process steps and lower yield penalties, making the low-power design more cost-effective despite the sophisticated operation required
3Use of energy by moving object
If a bandgap reference circuit uses a three-state design to achieve low power operation, then power consumption is reduced, but device complexity and start-up circuit requirements increase
Solution Approach 1:
The patent extracts and removes the complex start-up circuitry typically required for three-state designs. By operating with only two p-n junctions and two stable states, the circuit eliminates the need for sophisticated start-up mechanisms, thereby reducing overall device complexity while maintaining low power consumption through simplified state management
Solution Approach 2:
Instead of using a three-state design that requires complex start-up circuits to manage multiple stable states, the patent inverts the approach by using a two-state design. This inversion simplifies the start-up requirements and reduces device complexity while achieving low power consumption through the reduced number of states and associated control circuitry
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 solution achieves low-power, low-voltage, and temperature-independent reference voltage generation with reduced manufacturing complexity and cost, enabling efficient and compact electronic component design.
Implementation Method 1
a first servo loop (e.g., a PTAT servo loop) comprising a first p-n junction with a first current density and a second p-n junction with a second current density different than the first current density
Implementation Method 2
a second servo loop (e.g., a CTAT servo loop) shares the first or the second p-n junction of the first servo loop
Implementation Method 3
a resistor coupled to the two servo loops and ground, wherein the voltage across the resistor is the reference voltage output
Data Source
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AI summary
Disclosed is a fractional bandgap circuit and method to provide a same reference voltage value in a variety of circumstances of operation, including variations in manufacturing process, temperature, and a supply voltage. The disclosed fractional bandgap circuit and method also allows for low supply voltage operation within a compact layout area.