Charge-Pump Voltage Boosting Device With Reduced Ripple
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Solution Overview
Problem
Existing charge-pump voltage-boosting devices for non-volatile flash memories suffer from significant output ripple, which affects the precision of voltage control, especially in multilevel flash memories, and existing solutions do not provide a general, effective method to reduce this ripple.
Innovation Solution
A charge-pump voltage-boosting device with a control circuit that uses multiple comparators to generate enabling signals for sets of series-connected stages, allowing for independent activation and deactivation based on output voltage levels, thereby reducing ripple.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If a charge pump with multiple series-connected stages is used to achieve high output voltage, then the output voltage level is improved, but the output voltage ripple increases significantly
Solution Approach 1:
The charge pump is divided into multiple independent stages that can be selectively activated. Each stage can be controlled independently through separate enabling signals, allowing the pump to operate with fewer stages at certain times, thereby reducing output ripple while maintaining the capability to generate high voltages when needed.
Solution Approach 2:
The charge pump transitions from a static configuration where all stages are always active to a dynamic configuration where stages can be selectively enabled or disabled. This dynamic control allows optimization of the operating point to minimize ripple while maintaining voltage boosting capability.
2Device complexity
If simple ON/OFF regulation is used to control output voltage, then device complexity is reduced, but measurement precision of output voltage control deteriorates
Solution Approach 1:
The control system is segmented into multiple comparators, each responsible for monitoring a specific voltage threshold. This segmentation allows for more granular control of the charge pump stages, improving voltage control precision without requiring a single complex high-precision comparator.
Solution Approach 2:
Multiple comparators provide feedback signals based on different voltage thresholds, enabling more precise regulation of the output voltage. The feedback mechanism allows the system to respond to different voltage conditions with appropriate stage activation, improving control precision.
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 approach results in a substantial reduction of output ripple, improving voltage control precision and power-supply rejection ratio, as demonstrated by simulations showing a 67% reduction in peak-to-peak ripple.
Implementation Method 1
A first input of a plurality of comparators is connected to an output of the divider and receives a divided voltage; a second input of the comparators is connected to a respective output of a reference generator and receives a reference voltage
Data Source
AI summary
Voltage-boosting device having a supply input receiving a supply voltage, and a high-voltage output. The device is formed by a plurality of charge-pump stages series-connected between the supply input and the high-voltage output. Each charge-pump stage has a respective enabling input receiving an enabling signal. A control circuit formed by a plurality of comparators is connected to the high-voltage output and generates the enabling signals on the basis of the comparison between the voltage on the high-voltage output and a plurality of reference voltages, one for each comparator. The charge-pump stages are grouped into sets of stages, and the stages belonging to a same set receive a same enabling signal; thus, as many comparators as there are sets of stages are present.