Flash Memory Voltage Regulator with Dual Switches for Ripple Control
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Solution Overview
Problem
Flash memory devices experience instability and ripple in regulated voltages when external high voltage is applied, leading to operational errors and increased program loop iterations due to overshoot and ripple in the voltage waveform.
Innovation Solution
A voltage regulator with two switches having different switching current characteristics, where a switch with a low switching current is activated during external high voltage mode to prevent overshoot and ripple, and a switch with a high switching current is used for internal pumping voltage regulation, allowing for stable voltage output.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a switch with high switching current is used for regulating external high voltage, then the regulated voltage rises quickly, but overshoot and ripple occur in the voltage waveform
Solution Approach 1:
The patent employs dynamic switching control where the controller selectively activates different switches based on operating conditions. During initial voltage rise, a first switch with lower switching current is activated to prevent overshoot. Once the voltage reaches a predetermined level, a second switch with higher switching current is activated to maintain fast response. This dynamic adaptation resolves the contradiction between fast rising time and voltage stability.
Solution Approach 2:
The voltage regulator is segmented into multiple switches with different current characteristics, each handling specific phases of voltage regulation. The first switch handles the initial charging phase with lower current to avoid overshoot, while the second switch handles the maintenance phase with higher current for speed. This segmentation allows optimization of both speed and stability without compromise.
2Reliability
If a switch with low switching current is used for regulating external high voltage, then overshoot and ripple are reduced, but the rising time of regulated voltage increases
Solution Approach 1:
The system dynamically transitions from a low-current switch during the initial voltage rise phase to a high-current switch once the voltage reaches the target level. This dynamic switching strategy allows the system to benefit from both low overshoot (initial phase) and fast response (maintenance phase), resolving the contradiction between stability and speed.
Solution Approach 2:
The controller预先 activates the first switch with lower switching current before the voltage reaches the target level, preventing overshoot in advance. This preliminary action ensures stable voltage establishment, and only after this preliminary phase does the system switch to the second switch for maintaining speed.
3Reliability
If feedback operation is used for voltage regulation, then voltage stability is improved, but sensing delay causes ripple in the voltage waveform
Solution Approach 1:
The controller activates the first switch with lower switching current before the feedback loop can cause significant ripple. This preliminary action of controlled charging prevents the feedback sensing delay from manifesting as harmful ripple, while still maintaining voltage stability through the subsequent feedback operation.
Solution Approach 2:
The switching operation is segmented into two phases: initial charging with the first switch (lower current) to minimize ripple, and maintenance charging with the second switch (higher current) for speed. This segmentation isolates the feedback sensing delay effect to the first phase where it causes minimal harm, while the second phase benefits from faster response.
Data Source
AI summary
Provided is a voltage regulator of a flash memory device. Embodiments of the invention provide a voltage regulator that is configured to regulate either an internal pumping voltage or an external high voltage. In embodiments of the invention, the voltage regulator includes two switches having different switching current characteristics: when regulating the internal pumping voltage, the voltage regulator is configured to activate a switch having a relatively high switching current to output the regulated voltage; but when regulating the high external voltage, the voltage regulator is configured to activate a switch having a relatively low switching current to output the regulated voltage during at least a set-up time. In an embodiment of the invention, the voltage regulator may be configured to activate both switches to regulate the high external voltage after the set-up time. In yet another embodiment of the invention, after the set-up time, the voltage regulator may be configured to deactivate the switch having the relatively low switching current and activate the switch having the relatively high switching current to regulate the high external voltage.