Charge Pump Circuit with Triple-Well Bulk Tracking
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Solution Overview
Problem
Existing capacitive voltage multiplier circuits face inefficiencies when operating at low power supply voltages due to diode threshold voltages, requiring more stages and increasing power consumption, which degrades performance and reliability.
Innovation Solution
The implementation of a Charge Pump Circuit using multiphase control signals and MOSFETs in triple-well technology, with bulk voltage potential tracking, reduces threshold voltages and oxide stress, allowing for efficient high voltage generation from low input voltages without increasing transistor breakdown voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If conventional capacitive voltage multiplier circuits are used to generate high voltage from low power supply voltages, then voltage multiplication is achieved, but diode threshold voltages cause inefficiencies and increased power consumption
Solution Approach 1:
The patent changes the operating parameters of the voltage multiplier circuit by using triple-well MOSFETs with adjustable bulk voltage potentials. This allows the threshold voltage of the transistors to be reduced and optimized for low-power operation, thereby improving pumping efficiency and reducing power consumption simultaneously. The bulk voltage potential tracking mechanism dynamically adjusts the transistor parameters to maintain optimal operation across different input voltage conditions.
2Reliability
If more stages are added to overcome diode threshold voltage limitations, then voltage multiplication capability is improved, but power consumption increases
Solution Approach 1:
Instead of simply adding more stages, the patent changes the parameter of existing stages by using triple-well MOSFETs with reduced threshold voltages. This allows each stage to be more efficient, so fewer stages are needed to achieve the same voltage multiplication, thereby reducing overall power consumption while maintaining voltage multiplication capability.
Solution Approach 2:
The patent substitutes the conventional diode-based voltage multiplier mechanism with a MOSFET-based charge pump mechanism. This substitution allows for controlled threshold voltage through bulk potential adjustment, replacing the fixed threshold voltage characteristic of diodes with a tunable parameter that can be optimized for efficiency.
3Reliability
If triple-well MOSFETs with bulk voltage potential tracking are used, then threshold voltages are reduced and pumping efficiency is enhanced, but device complexity increases
Solution Approach 1:
The triple-well MOSFET structure serves multiple functions: it acts as the switching element, the charge storage element, and the voltage regulation element simultaneously. The bulk voltage potential tracking mechanism provides both threshold voltage reduction and automatic adaptation to input voltage variations, eliminating the need for separate control circuits for each function.
Solution Approach 2:
The bulk voltage potential tracking mechanism automatically adjusts the transistor parameters based on the input voltage conditions without external intervention. The circuit self-regulates to maintain optimal operation, reducing the need for complex external control circuitry and manual parameter adjustment.
4Reliability
If more serially connected stages are implemented, then high voltage generation capability is improved, but oxide stress on transistors increases
Solution Approach 1:
The patent changes the voltage distribution parameters across the transistor stages by using bulk voltage potential tracking. This ensures that the voltage stress on each transistor's oxide layer is optimized and kept within safe limits, even when multiple stages are connected in series. The triple-well structure allows for independent bulk voltage control of each stage, distributing the stress more evenly.
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 enhances pumping efficiency, reduces power consumption, and increases the number of serially connected stages, enabling high voltage generation with improved reliability and faster dynamic response.
Implementation Method 1
capacitive voltage multiplier circuits using MOS transistors
Implementation Method 2
Charge pumps are circuits that pump charge into capacitors to develop an output voltage higher than the supply voltage
Data Source
AI summary
A circuit and method are given, to realize a high efficiency voltage multiplier for integrated circuits generating an internal and flexible positive or negative high voltage on-chip supply voltage from low external positive or negative supply voltages or ground. Applying multi-phase control signals to voltage boost internal nodes allows for eliminating threshold voltage drop losses and thus improves the voltage pumping gain compared to circuits with diode-configured FETs of prior art. Making use of voltage signals from antecedent stages in order to bias the bulk of MOS transistors fabricated in triple-well technology enables relaxing of the gate oxide stress within high order stage MOS transistors. Such a method, called leap-frog bulk potential tracking method, makes MOS transistors from different stages exhibit about the same body effect, which is very important because MOS transistors of higher order stages now show the same performance as MOS transistors from lower order stages. Important also in terms of efficiency as the charge sharing speed of high order MOS transistors always dominates the total charge pump performance and the driving force of pumped currents, thus also allowing for a greater number of serially connectable stages overall or a smaller number necessary for a certain targeted output voltage.