Charge Pump Driving Circuit for N-Channel MOSFET Power Management
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Solution Overview
Problem
Current power management devices rely heavily on P-channel MOSFETs due to the high driving voltage required for N-channel MOSFETs, leading to increased power dissipation and costs, as P-channel switches have higher ON-state resistances and require specialized fabrication.
Innovation Solution
A driving circuit incorporating a charge pump unit and drivers to generate a higher output voltage for N-channel MOSFETs, enabling them to be fully switched on and off efficiently, thereby reducing power dissipation and increasing power transfer efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If N-channel MOSFETs are used to reduce power dissipation, then power transfer efficiency is improved, but high driving voltage is required which is not always available
Solution Approach 1:
A charge pump circuit is introduced as an intermediary device between the control signal and the N-channel MOSFET gate. The charge pump converts a lower input voltage into a higher output voltage capable of fully driving the N-channel MOSFET, thus enabling the use of low-on-resistance switches without requiring externally available high voltages.
Solution Approach 2:
The invention dynamically changes the voltage parameter at the MOSFET gate by using a charge pump that generates a time-varying high voltage signal. This allows the gate voltage to exceed the source voltage during switching operations, enabling complete turn-on and turn-off of the N-channel MOSFET while maintaining compatibility with standard power source voltage levels.
2Ease of operation
If P-channel MOSFETs are used to simplify driving, then ease of operation is improved, but ON-state resistance increases leading to higher power dissipation
Solution Approach 1:
Instead of using P-channel MOSFETs which are easier to drive but have higher resistance, the invention inverts the conventional approach by using N-channel MOSFETs (which have lower resistance but are harder to drive) and solving the driving difficulty through a charge pump circuit. This inversion allows achieving lower power dissipation while maintaining ease of operation through the charge pump's automatic voltage generation.
3Loss of energy
If low ON-state resistance PMOS switches are used to reduce power dissipation, then power transfer efficiency is improved, but fabrication cost and chip area increase
Solution Approach 1:
The invention uses standard, commonly available N-channel MOSFETs and P-channel MOSFETs with standard fabrication processes. Instead of requiring expensive specialized low-resistance PMOS fabrication, the solution copies the successful low-resistance NMOS design approach and applies it to power management by adding a charge pump, thereby achieving similar performance benefits without the high fabrication costs.
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 use of N-channel MOSFETs with the proposed driving circuit reduces power dissipation and increases power transfer efficiency, while maintaining lower costs compared to P-channel switches, with minimal impact on overall efficiency.
Implementation Method 1
a charge pump unit and a driver coupled to the charge pump. In such an embodiment, the charge pump receives a source voltage and outputs an output voltage higher than the source voltage
Data Source
AI summary
A driving circuit for an N-channel Metal Oxide Semiconductor (NMOS) transistor can include a charge pump unit and a driver coupled to the charge pump. The charge pump can receive a source voltage and output an output voltage higher than the source voltage, where the source voltage is applied to a source terminal of the NMOS transistor. The driver receives the output voltage of the charge pump unit and converts the output voltage to a driving voltage operable for conducting the NMOS transistor.