Cascode Gate Driver Slew-Rate Control for Ringing and EMI
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional cascode switch devices lack effective control over the switching slew rate of the drain voltage, leading to excessive ringing and high electromagnetic interference, and high power dissipation due to voltage spikes during switching transitions.
Innovation Solution
A cascode switch device with a gate driver configured to provide a gate driver signal to control the switching slew rate of the normally-on switch device, incorporating a current limiting circuit to manage gate current and a timing circuit to optimize switching speed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If conventional cascode configuration is used without slew rate control, then the circuit structure is simple, but excessive ringing and electromagnetic interference occur
Solution Approach 1:
The patent introduces a gate driver circuit as an intermediary component between the control signal and the normally-on switch device. This gate driver includes a current limiting circuit and timing circuit that mediate the switching process, controlling the gate voltage transition to manage the slew rate of drain voltage and reduce ringing and EMI without fundamentally changing the cascode structure
2Speed
If high voltage spike is allowed during switching transition, then the switching speed is fast, but power dissipation increases due to voltage above safe operating limits
Solution Approach 1:
The patent changes the voltage parameter profile during switching transitions by controlling the gate voltage waveform. The current limiting circuit and timing circuit work together to shape the gate voltage transition, thereby controlling the drain voltage slew rate to stay within safe operating limits while maintaining efficient switching speed
3Device complexity
If switching slew rate is not controlled, then the gate driver circuit is simple, but system stability deteriorates due to excessive ringing
Solution Approach 1:
The gate driver circuit incorporates timing circuits that provide feedback control on the switching process. By monitoring and controlling the gate voltage transition timing, the circuit regulates the drain voltage slew rate to prevent excessive ringing and maintain system stability
Data Source
AI summary
A cascode switch device includes a normally-on switch device, a normally-off switch device, and a gate driver. The normally-on switch device has a first terminal, a second terminal and a control terminal. The normally-off switch device has a first terminal, a second terminal and a control terminal. The first terminal of the normally-off switch device is coupled to the second terminal of the normally-on switch device, and the control terminal of the normally-off switch device is coupled to the control terminal of the normally-on switch device. The gate driver is configured to provide a gate driver signal to the control terminal of the normally-on switch device to control a switching slew rate of a voltage at the first terminal of the normally-on switch device. The normally-on switch device is turned on or turned off in response to the gate driver signal.