Voltage Mirror Circuit for Negative Voltage Generation
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Solution Overview
Problem
Existing electronic circuit designs for negative voltage generation stress the gate oxide of devices, limiting their ability to change logic states after the low logic voltage level has been lowered, which can lead to device damage.
Innovation Solution
A circuit configuration that includes a negative voltage generation circuit with a charge pump, comparator, and bypass transistors, allowing the level shifters to change logic states at an intermediate negative voltage level, enabling regulation of both intermediate and final negative voltage levels without requiring a separate negative voltage source, and incorporating protection circuitry to manage impact ionization current.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If charge pump circuits are used to generate negative voltage, then negative voltage can be generated, but the circuit occupies large chip area and consumes large quiescent current
Solution Approach 1:
The patent replaces the traditional charge pump circuit (electromechanical approach) with a voltage mirror circuit based on MOS transistor characteristics. This substitution eliminates the need for mechanical switching components and large capacitors, significantly reducing chip area while lowering quiescent current consumption through the high-impedance characteristics of the voltage mirror configuration.
Solution Approach 2:
The patent changes the operating parameters by using the voltage mirror circuit to replicate and invert the reference voltage signal. By adjusting the transistor dimensions and biasing conditions, the circuit achieves negative voltage generation with optimized current consumption and area utilization, transforming the fundamental operating mode from charge pumping to voltage mirroring.
2Quantity of substance
If charge pump circuits are used to generate negative voltage, then negative voltage can be generated, but the circuit structure is complex
Solution Approach 1:
The patent replaces the complex charge pump circuit structure with a simplified voltage mirror implementation using a minimal number of MOS transistors. This substitution eliminates multiple switching elements, control logic, and large energy storage components, resulting in a structurally simple circuit that achieves the same negative voltage generation function with fewer parts and lower complexity.
3Reliability
If operational amplifiers are used for voltage mirroring, then voltage can be mirrored, but it is difficult to achieve high input impedance
Solution Approach 1:
The patent substitutes operational amplifiers with a direct MOS transistor-based voltage mirror configuration. This replacement inherently provides high input impedance due to the high-impedance gate terminals of the MOS transistors, eliminating the need for additional buffering stages or complex compensation networks required by op-amp implementations.
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
Enables the generation of negative voltages that allow logic circuitry to operate and change states at intermediate negative values, reducing the risk of device damage and eliminating the need for additional negative voltage sources, thereby enhancing the reliability and flexibility of negative voltage regulation in electronic circuits.
Implementation Method 1
a first capacitor coupling the inverted output signal to a second capacitor
Implementation Method 2
a voltage mirror circuit including a first capacitor coupling the inverted output signal to a second capacitor
Data Source
Figure 1
Figure 2
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AI summary
A first logic state is at a first output voltage level at a first output of a level shifter (225) that selects a first negative regulation voltage level in response to the first logic state. A negative supply voltage begins at first potential and decreases to the first negative regulation voltage level. The first output voltage level decreases as the negative supply voltage decreases. The first output of the level shifter (225) is switched from the first logic state to a second logic state in response to the negative supply voltage reaching the first negative regulation voltage level. The second logic state is provided at a second output voltage level that selects a second negative regulation voltage level for the negative regulation voltage. The first output of the level shifter remains at the second logic state but is reduced in voltage.