Fractional Negative Charge Pump for Low-Leakage Gate Biasing
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Solution Overview
Problem
Existing charge pumps fail to generate a fractional negative voltage output from a positive voltage input, leading to issues such as excessive negative voltage magnitude, gate-induced drain leakage, and increased power consumption due to current leakage in modern FET-based circuitry.
Innovation Solution
A charge pump design that outputs a fractional negative voltage by connecting fly capacitors in series during charging and parallel during discharging, using complementary clock signals to achieve a lower magnitude negative voltage, and incorporating feedback control for dynamic adjustment based on transistor performance variations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If conventional charge pumps are used to generate negative voltage from positive input, then voltage conversion is achieved, but the output voltage magnitude is excessive and causes gate-induced drain leakage
Solution Approach 1:
The patent divides the single large-capacitor charge pump into multiple smaller capacitors (first, second, third capacitors) connected in series during charging. This segmentation allows the total voltage to be distributed across multiple elements, enabling fractional voltage output (e.g., 1/3 of input voltage) and preventing excessive voltage magnitude that causes gate-induced drain leakage.
Solution Approach 2:
The patent dynamically reconfigures the capacitor connections based on operating phase: during charging, capacitors are connected in series to generate the negative voltage; during discharging, they are reconfigured to maintain stable output. This dynamic switching enables precise control of output voltage magnitude to avoid harmful leakage effects.
2Power
If conventional charge pumps are used, then voltage conversion is achieved, but power consumption increases due to current leakage
Solution Approach 1:
By segmenting the charge pump into multiple capacitors and switches, the patent reduces current leakage in each individual component. The distributed architecture ensures that no single transistor or capacitor bears the full voltage stress, thereby minimizing leakage current and reducing overall power consumption.
Solution Approach 2:
The patent changes the voltage parameter distribution across the circuit by using series-connected capacitors during charging. This parameter transformation reduces the voltage stress on individual transistors, thereby reducing their leakage current and overall power consumption of the charge pump.
3Power
If fly capacitors are connected in series during charging, then fractional negative voltage is achieved, but circuit complexity increases
Solution Approach 1:
The patent designs the circuit so that the same set of capacitors and switches serves multiple functions: during the charging phase, capacitors are connected in series to generate fractional negative voltage; during the discharging phase, the same components are reconfigured to maintain stable output and regulate voltage. This multi-functionality reduces the need for separate component sets, thereby limiting the increase in circuit complexity.
Solution Approach 2:
The patent uses periodic switching between charging and discharging phases to achieve fractional voltage output. The regular alternation between series connection (for voltage division) and parallel connection (for output stabilization) allows the circuit to maintain simplicity through predictable, repeating patterns rather than requiring complex continuous control.
4Stability of the object's composition
If dynamic feedback control is implemented, then output stability is improved, but control circuit complexity increases
Solution Approach 1:
The patent implements a feedback control mechanism where the output voltage is monitored and compared against a reference, and the switching signals are adjusted accordingly to maintain stable output. This feedback ensures that despite variations in load or input voltage, the fractional negative voltage remains stable and precise.
Solution Approach 2:
The charge pump circuit monitors its own output and automatically adjusts its switching behavior to maintain stability. The control circuitry is integrated within the charge pump itself, allowing it to self-regulate without requiring external complex control systems, thereby limiting the increase in overall control circuit complexity.
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
The solution provides a stable, lower magnitude negative voltage suitable for gate biasing, reducing power consumption and minimizing electronic noise, while maintaining balanced output voltage under varying load conditions.
Implementation Method 1
A charge pump uses capacitors, referred to as fly capacitors, to transfer charge from an input voltage to an output voltage
Data Source
AI summary
Charge pump circuits having a fractional negative voltage output from a positive voltage input. A control circuit provides for feedback control of the output of such a charge pump, and may include dynamic adjustment of the charge pump output based on one or more factors. In some embodiments, two or more charge pumps are coupled in a differential configuration such that while one set of capacitors are in series charging, at least one other set of capacitors is discharging. One embodiment encompasses a fractional negative voltage charge pump including n≥2 capacitors configured to be coupled in series between an input voltage and ground during a charging phase, and in parallel between ground and an output terminal during a discharging phase. The fractional negative voltage charge pump outputs a negative voltage that is no more than 1/n of a positive voltage input in magnitude.