Negative Voltage Charge Pump With Feedback Frequency Control
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Solution Overview
Problem
Integrated circuits requiring negative voltage sources often rely on external components like inverting converters or transformers, which can be large and expensive, necessitating a more compact and cost-effective internal generation solution.
Innovation Solution
A circuit that generates a negative voltage internally using a negative voltage generation circuit, oscillator, and oscillator control signal generator, dynamically adjusting the frequency of the oscillating signal to match the load demand and maintain accurate voltage levels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If external negative voltage sources (inverting converters or transformers) are used, then reliable negative voltage supply is achieved, but device size and cost increase
Solution Approach 1:
The patent extracts the negative voltage generation function from external components and implements it internally within the integrated circuit using a charge pump circuit. This eliminates the need for external inverting converters or transformers, thereby reducing device size and cost while maintaining reliable negative voltage supply through integrated capacitors and switches.
Solution Approach 2:
The patent replaces mechanical/electromagnetic components (transformers, inverting converters) with a solid-state charge pump circuit using capacitors and electronic switches. This substitution of mechanical systems with electronic components enables internal integration, reducing size and cost while achieving the same negative voltage generation function.
2Ease of operation
If fixed frequency oscillation is used, then circuit operation is simplified, but negative voltage accuracy under varying load conditions deteriorates
Solution Approach 1:
The patent implements a feedback mechanism where the oscillator control signal generator monitors the negative voltage level and dynamically adjusts the oscillation frequency. When the negative voltage deviates from the target level, the feedback loop modifies the frequency to increase or decrease charge pumping, thereby maintaining accurate negative voltage levels under varying load conditions while keeping the control logic integrated and manageable.
Data Source
AI summary
A circuit that is capable of generating a negative voltage on a negative voltage supply node. The circuit includes a negative voltage generation circuit, an oscillator and an oscillator control signal generator. The negative voltage generation circuit generates a negative voltage on the negative voltage supply node in response to receiving a signal from the oscillator. The negative voltage generated by the negative voltage generation circuit depends upon the frequency of the signal from the oscillator. The oscillator control signal generator controls the frequency of the signal from the oscillator by sensing the negative voltage present on the negative voltage supply node, and by increasing or decreasing the frequency of the signal from the oscillator accordingly. Thus, charge is replenished to the negative voltage supply node to more closely match the drawing of charge from that negative voltage supply node, thereby more accurately generating the negative voltage.