Charge Pump Switching Circuit With Reduced Parasitic Capacitance
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Solution Overview
Problem
The gate switching type charge pump circuit operates at low voltage but requires large capacitance to maintain current value, leading to increased circuit area.
Innovation Solution
The charge pump circuit is designed with transistors having identical channel widths and lengths, and switch elements that connect control terminals to ground or power supply nodes, reducing parasitic capacitance and circuit area.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If large capacitance is arranged to suppress decrease in current value, then current stability is improved, but circuit area increases
Solution Approach 1:
The invention changes the channel length parameter of the transistor to be sufficiently long, which inherently provides current stability without requiring large external capacitance. This parameter change allows the transistor itself to act as a current source with stable characteristics, resolving the contradiction between current stability and circuit area.
Solution Approach 2:
The invention makes the transistor serve dual functions: as a switching element and as a current source. By configuring the transistor with a sufficiently long channel, it inherently provides current stability without needing separate large capacitance components, making the circuit self-sufficient and reducing overall circuit area.
2Reliability
If sufficiently long channel length transistor is used, then current stability is improved, but transistor size increases
Solution Approach 1:
The invention merges the function of the current source transistor with the switching transistor into a single device. The transistor simultaneously performs switching and current source functions, eliminating the need for separate large capacitance components and reducing overall circuit area while maintaining current stability.
Solution Approach 2:
By optimizing the channel length parameter to be sufficiently long, the transistor achieves stable current characteristics inherent to its structure, reducing reliance on external capacitance and thereby reducing the total area occupied by the circuit components.
Data Source
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AI summary
The present technology relates to a charge pump circuit that enables reduction of a circuit area. Provided is a charge pump circuit including: a first transistor; a second transistor to which a constant current is supplied; a third transistor connected to the first transistor and a voltage source; a fourth transistor group including N transistors arranged in a cascade on the first transistor side, the N transistors all including control terminals connected to the second transistor; a fifth transistor group including N transistors arranged in a cascade on the second transistor side, the N transistors all including control terminals connected to the second transistor; a first switch that connects the first transistor to the second transistor; a second switch that connects the first transistor to a ground node; a third switch that connects the third transistor to the fifth transistor group; and a fourth switch that connects the third transistor to the ground node.