Dual-Oscillator Charge Pump Switching for Fast NFET Gate Drive
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing charge pumps struggle to provide sufficient charge to the gate of a switch NFET within a specified switching time requirement while minimizing electronic noise generation, especially when operating at high frequencies.
Innovation Solution
A dual-oscillator circuit is employed to output different frequency signals, using a slow oscillator for normal operation and a fast oscillator during switching events, coupled with a counter to control the frequency transition, thereby ensuring rapid charge delivery to NFETs without excessive noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the charge pump frequency is increased to speed up gate voltage ramp up, then the switching time requirement is met, but electronic noise generation increases
Solution Approach 1:
The patent applies periodic action by using a dual-oscillator system that alternates between low-frequency and high-frequency operation. During normal operation, a low-frequency oscillator runs to minimize noise. When switching is required, a high-frequency oscillator is activated for a specific duration (controlled by a counter) to rapidly charge the gate, then returns to low-frequency operation. This periodic switching between frequency states resolves the contradiction by providing high speed only when necessary while maintaining low noise during steady state.
Solution Approach 2:
The patent implements dynamics by making the charge pump frequency adaptive rather than fixed. The system dynamically adjusts the oscillator frequency based on operational requirements: low frequency during normal operation, high frequency during switching events. This dynamic frequency adjustment allows the system to optimize between speed and noise generation in real-time, resolving the technical contradiction.
2Loss of time
If a high frequency charge pump is used to meet short switching time requirements, then the NFET can be turned ON quickly, but the system performance degrades due to increased noise
Solution Approach 1:
The counter-controlled high-frequency activation implements periodic action by limiting high-frequency operation to specific time intervals (during switching events). The counter ensures the high-frequency oscillator operates only for the necessary duration to meet switching requirements, then automatically returns to low-frequency mode. This resolves the contradiction by confining high-speed operation to brief periodic intervals rather than continuous operation.
Solution Approach 2:
The patent applies parameter changes by dynamically modifying the frequency parameter of the charge pump oscillator based on operational state. The system changes from low-frequency to high-frequency operation during switching events, then returns to low-frequency operation. This parameter adjustment allows the system to achieve fast switching when needed while maintaining low noise during normal operation.
3Object-generated harmful factors
If the charge pump operates at low frequency to minimize noise, then electronic noise is reduced, but the gate capacitance cannot be charged quickly enough to meet switching time requirements
Solution Approach 1:
The dual-oscillator system with counter control implements dynamics by adapting the charge pump frequency to operational requirements. During normal operation, the system uses low-frequency mode to minimize noise. When switching is detected (via the counter), the system dynamically switches to high-frequency mode to rapidly charge the gate capacitance, then returns to low-frequency mode. This dynamic adaptation resolves the contradiction between noise minimization and fast charge delivery.
Solution Approach 2:
The system applies periodic action by alternating between low-frequency and high-frequency operation based on switching events. The counter controls the duration of high-frequency bursts, creating a periodic pattern of high-speed charging followed by low-noise operation. This periodic alternation allows the system to achieve fast charge delivery when needed while maintaining low noise during the majority of operation.
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 enables charge pumps to meet switching time requirements with minimal electronic noise by optimizing frequency operation, eliminating the need for large external capacitors and reducing noise levels during non-switching periods.
Implementation Method 1
Charge pumps generally require a periodic clock signal input that allows one or more capacitors to be charged in a first circuit configuration and discharged in a second circuit configuration such that an input voltage is converted to an output voltage at a different potential.
Data Source
AI summary
Circuits and methods that enable a charge pump to provide sufficient charge to the gate of a switch NFET to turn the NFET ON within a specified switching time requirement but with minimal generation of electronic noise. An embodiment includes a dual-oscillator circuit configured to output from a first oscillator a first frequency signal from a first oscillator during normal operation, and to output from a second oscillator a second frequency signal higher in frequency than the first frequency signal for a selected time determined by a counter. An embodiment includes a charge pump coupled to the dual-oscillator circuit and configured to output an electrical charge as a function of an applied frequency signal from the dual-oscillator circuit, wherein application of the second frequency signal output during counting increases the amount of electrical charge output by the charge pump.