Bi-directional Charge Pump Circuit for Low Voltage Applications
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Solution Overview
Problem
Conventional charge pumps are limited in generating high positive and negative voltages at low supply voltages, requiring multiple units, consuming significant area, and experiencing reduced output current due to leakage issues, making them unsuitable for modern high-density semiconductor devices.
Innovation Solution
A bi-directional charge pump system utilizing a basic stage and a bi-directional stage with boosting capacitors and N-type devices, capable of operating in both positive and negative configurations, to generate high voltages efficiently at very low supply voltages, reducing the need for multiple pumps and minimizing area consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If conventional charge pump is used to generate high voltage, then voltage above supply voltage can be provided, but output current decreases and leakage increases at low supply voltages
Solution Approach 1:
The patent changes the operating parameters by using thick-oxide high-voltage transistors instead of thin-oxide low-voltage transistors. This parameter change allows the charge pump to operate at low supply voltages (e.g., 1.8V) while generating high voltages (e.g., 12V) without excessive leakage, because the thick oxide prevents breakdown leakage even when large voltage drops occur between gate and bulk.
Solution Approach 2:
The patent segments the charge pump into multiple capacitor-diode pairs (at least three stages) cascaded together. Each stage contributes to the overall voltage multiplication, and the segmentation allows the system to achieve high voltage gain while maintaining adequate output current by distributing the voltage stress across multiple stages rather than concentrating it in a single stage.
2Use of energy by moving object
If multiple capacitor-diode pairs are cascaded to increase voltage gain, then higher voltage can be achieved, but area consumption increases significantly
Solution Approach 1:
The patent makes the charge pump bi-directional by adding a bi-directional stage that can operate in both positive and negative configurations. This multi-functionality allows a single charge pump circuit to provide both high positive voltage (for programming) and high negative voltage (for erasing), eliminating the need for separate charge pumps and thereby reducing the total area consumption while maintaining high voltage gain capability.
Solution Approach 2:
The patent merges the functionality of two separate charge pumps (one for positive voltage, one for negative voltage) into a single bi-directional charge pump. By combining the positive voltage generation path and negative voltage generation path in one integrated circuit, the patent reduces the overall area consumption while achieving the same voltage gain in both directions.
3Reliability
If thick oxide high voltage transistors are used to sustain large voltage drop, then reliability improves, but device complexity and cost increase
Solution Approach 1:
The patent applies local quality by using thick-oxide high-voltage transistors specifically in the capacitor-diode pairs where large voltage drops between gate and bulk occur, while other parts of the circuit can use standard thin-oxide low-voltage transistors. This localized application of high-voltage devices only where necessary reduces the overall device complexity and cost while maintaining the reliability needed for voltage sustain capability.
4Use of energy by stationary object
If conventional charge pump operates at low supply voltage, then power consumption decreases, but output current capability is reduced
Solution Approach 1:
The patent changes the transistor oxide thickness parameter to thick oxide, which fundamentally alters the leakage characteristics. This parameter change enables the charge pump to operate at low supply voltages (reducing power consumption) while maintaining high output current capability, because the thick oxide prevents breakdown leakage that would otherwise limit the output current at low supply voltages.
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 bi-directional charge pump system effectively provides high positive and negative voltages with sufficient output current, even at low supply voltages, while reducing area consumption and overcoming leakage issues, making it suitable for high-density semiconductor applications.
Implementation Method 1
at least one pumping capacitor coupled with the first pumping node
Implementation Method 2
at least a first and a second auxiliary capacitor for providing an overshoot for the at least one device
Implementation Method 3
at least one device coupled with the pumping node(s)
Data Source
AI summary
A method and system for providing an output voltage greater than a voltage of a voltage supply in a semiconductor device are disclosed. The method and system include providing basic stage(s) and/or a bi-directional stage and basic stage(s) coupled with the bi-directional stage. The bi-directional stage includes boosting capacitors, N-type devices, and an interface and allows operation in positive or negative configurations. A first of the basic stage(s) is coupled with the interface. The basic stage includes first and second sections. The first section includes pumping node(s) coupled with pumping capacitor(s), device(s) coupled with the pumping node(s), and auxiliary capacitors for providing an overshoot for the device(s) for value(s) of the clock signals. The second section is analogous to the first section. A clock provides clock signals to the first and second sections and the bi-directional stage. The first and second sections alternately charge and fully discharge based on the clock signals.