Bandgap Reference Voltage Circuit with Substrate Noise Reduction
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Solution Overview
Problem
Existing bandgap reference voltage circuits are limited in providing different levels of reference voltages and are sensitive to substrate injections and noises, which affect their stability and accuracy.
Innovation Solution
A circuit configuration using a bipolar assembly with p-n-p bipolar transistors, where the bases are coupled to a fixed voltage, and a module balances currents in parallel branches, incorporating a p-n junction and resistors with specific temperature coefficients to generate a stable bandgap reference voltage, reducing substrate noise influence and allowing for adjustable reference voltages.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If diode-connected bipolar transistors are used in existing bandgap reference circuits, then the circuit can provide a stable reference voltage, but the circuit becomes sensitive to substrate injections and noises
Solution Approach 1:
The patent extracts the problematic diode-connected configuration and replaces it with separate transistor structures where the base is directly connected to the reference node. This separation removes the substrate noise coupling path that exists in diode-connected transistors, thereby eliminating the harmful sensitivity to substrate injections while maintaining the voltage reference function.
Solution Approach 2:
The patent introduces an operational amplifier as an intermediary element that actively maintains the base voltage at the reference node. This active control mechanism mediates between the transistor and the reference node, ensuring stable operation while isolating the transistor from substrate noise effects, thus resolving the contradiction between stability and noise sensitivity.
2Adaptability or versatility
If existing bandgap reference circuit configurations are used, then a reference voltage of 1.25V is provided, but the circuit cannot meet requirements for different levels or higher levels of reference voltages
Solution Approach 1:
The patent creates a universal bandgap reference circuit architecture that can provide multiple reference voltage levels (1.25V, 2.5V, and higher) through configurable switching elements. The same core circuit structure can be adapted to different voltage requirements by enabling or disabling specific transistors and adjusting resistor ratios, making the circuit multi-functional without requiring separate designs for each voltage level.
Solution Approach 2:
The patent introduces dynamic configurability through switching elements that can be controlled to change the circuit's operation mode. By dynamically adjusting which transistors are active and how the current paths are configured, the reference voltage level can be changed on-the-fly, providing adaptability while maintaining a relatively simple base circuit structure.
3Use of energy by moving object
If conventional bandgap reference circuits are used, then a fixed reference voltage is generated, but additional reference current circuits are needed increasing power consumption
Solution Approach 1:
The patent merges the reference voltage generation function and reference current generation function into a single integrated circuit structure. The same bipolar transistors, resistors, and operational amplifier that generate the bandgap reference voltage also provide stable reference currents to other circuits. This consolidation eliminates the need for separate reference current circuits, reducing power consumption while maintaining circuit stability.
Solution Approach 2:
The patent designs the bandgap reference circuit to serve multiple functions simultaneously: it generates a stable reference voltage for voltage regulation and provides stable reference currents for other analog circuits. This multi-functionality allows a single circuit structure to replace what would traditionally require separate dedicated circuits, thereby reducing overall power consumption and device complexity.
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 provides a stable, substrate-current-insensitive bandgap reference voltage and temperature-insensitive reference current, enabling low-power applications and reducing the need for additional reference current circuits, while allowing for adjustable voltage levels.
Implementation Method 1
where VT is the thermal voltage, R1, R2 and R3 are resistances of resistors 1, 2 and 3
Implementation Method 2
The second resistor comprises at least two types of resistors with different temperature coefficients, being configured so that the second resistor has a temperature coefficient in a range of 3000 ppm/K to 3500 ppm/K
Data Source
AI summary
A bandgap reference voltage generator includes a bipolar assembly having a first resistor, a first branch and a second branch that is in parallel with the first branch. The first branch includes a first bipolar transistor with a base coupled to a fixed voltage. The second branch includes a second bipolar transistor with a base coupled to the fixed voltage and a second resistor coupled in series with the second bipolar transistor. A differential module is coupled to the first and second bipolar transistors and configured to balance the currents in the first and the second branches. The bandgap reference voltage is output at a node to which the first resistor is connected.