Low Voltage Charge Pump for High Output Voltage
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Solution Overview
Problem
High voltage charge pumps require large area and high parasitics, leading to increased device current consumption due to the use of high voltage devices, which is inefficient for generating high voltages from low on-chip supply levels in non-volatile memory devices.
Innovation Solution
A high voltage charge pump design utilizing low voltage devices for capacitors and switches, with a specific topology that connects capacitors in series and uses PMOS transistors to manage voltage differences, reducing area requirements and current consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If high voltage devices are used in charge pumps, then high output voltage is achieved, but area consumption and current consumption increase
Solution Approach 1:
The charge pump circuit is divided into multiple stages, each generating a portion of the total voltage boost. Multiple capacitors are used in series to distribute the voltage multiplication across stages, allowing low voltage devices to be used in each stage while achieving high overall output voltage.
Solution Approach 2:
Capacitors are introduced as intermediary energy storage elements between the low voltage input and the high voltage output. These capacitors temporarily store charge and enable voltage multiplication through series connection, acting as mediators that allow low voltage devices to generate high voltage output without directly承受 the full voltage stress.
2Power
If high voltage devices are used in charge pumps, then high output voltage is achieved, but current consumption increases
Solution Approach 1:
The current consumption is distributed across multiple low voltage device stages rather than being concentrated in single high voltage devices. Each stage operates at low voltage with lower individual current consumption, while the cumulative effect achieves the required high voltage output.
Solution Approach 2:
The operating voltage parameter of the devices is changed from high voltage to low voltage, which fundamentally reduces the current consumption since power consumption in MOS devices is proportional to the cube of the voltage. This parameter change is enabled by using capacitive voltage multiplication to achieve the high voltage output.
3Power
If high voltage devices are used in charge pumps, then high output voltage is achieved, but parasitic effects increase
Solution Approach 1:
The total voltage stress and associated parasitic effects are segmented across multiple low voltage devices and capacitors. Each device experiences only low voltage stress with minimal parasitic effects, while the series connection of capacitors accumulates the voltage without proportionally increasing parasitic losses.
4Area of moving object
If low voltage devices are used in charge pumps, then area and current consumption are reduced, but voltage difference support capability is limited
Solution Approach 1:
Capacitors are used as intermediary elements to bridge the voltage difference capability gap of low voltage devices. By connecting capacitors in series and using them to store and transfer charge, the system achieves high voltage output capability while individual low voltage devices only need to withstand low voltage differences.
Solution Approach 2:
The charge pump operates in continuous cyclic phases (charging phase and boosting phase), maintaining continuous useful action. During the charging phase, capacitors are charged from low voltage input; during the boosting phase, they are connected in series to generate high voltage output. This continuous cycling enables low voltage devices to achieve high voltage capability through time-multiplexed operation.
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 design effectively generates high output voltages while minimizing area and current consumption by using low voltage devices, reducing parasitic effects and adhering to electrical design rules, thus optimizing the performance of charge pumps in non-volatile memory systems.
Implementation Method 1
Charge pumps use a combination of switches and capacitors to provide a DC output voltage higher or lower than its DC input voltage. During one clock half cycle, the charging half cycle, the capacitor couples in parallel to the input so as to charge up to the input voltage.
Implementation Method 2
The switching circuitry includes: a first number of PMOS transistors connected in series between the first plate of the (M−1)st capacitor in the series and the second plate of the Mth capacitor in the series
Data Source
AI summary
A charge pump design suitable for generating high voltages employs multiple low voltage capacitors and low voltage transfer switches, with a limited number of high voltage devices. This is designed such that during a first clock phase, capacitors are each connected between an input voltage and ground and, during a second clock phase all the capacitors are connected in series to generate the required voltage. Both the switches (PMOS) and as well the capacitors are realized as low voltage devices. The ability to use low voltage devices can significantly reduce the area and also a reduction in current consumption relative to the usual high voltage charge pumps which uses high voltage devices.