GaN Pulse Generator Circuit for High-Frequency Ultrasound
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Solution Overview
Problem
Conventional silicon-based ultrasound pulsing circuits are unsuitable for applications requiring high energy delivery with ultra-long burst mode pulse length, multi-MHz pulse frequencies, and high pulse amplitude, such as ultrasound surgery and shear wave generation.
Innovation Solution
A high power gallium nitride (GaN) transistor-based pulse generator circuit is employed, featuring a transmitter beam former, gate drivers, snubber circuits, and a center-tapped transformer to generate high-energy pulsed signals for driving ultrasound transducer arrays.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If silicon-based pulsing circuits are used, then conventional ultrasound imaging is achieved, but high energy delivery with ultra-long burst mode and multi-MHz frequencies cannot be delivered
Solution Approach 1:
The patent changes the material parameter of the transistor from silicon to gallium nitride (GaN), which fundamentally alters the electrical characteristics including breakdown voltage, current density, and switching speed. This material substitution enables the circuit to deliver high energy with ultra-long burst mode and multi-MHz frequencies that silicon-based circuits cannot achieve.
2Power
If high power pulsing is achieved using GaN transistors, then efficiency and power handling improve, but voltage overshoot and electrical stress increase
Solution Approach 1:
The patent implements snubber circuits connected across the GaN transistors that act as protective elements to clamp voltage overshoot before it can damage the transistors. These snubber circuits absorb transient voltage spikes and electrical stress that occur during high-power switching operations, thereby protecting the GaN devices while enabling high power handling capability.
3Speed
If high frequency pulsing is implemented, then ultrasound resolution improves, but power losses increase in silicon-based systems
Solution Approach 1:
The patent changes the material parameter from silicon to gallium nitride, which fundamentally improves the frequency response characteristics and reduces resistive losses. GaN's superior electron mobility and lower on-resistance enable high-frequency pulsing with significantly reduced power losses compared to silicon-based systems, allowing efficient operation at multi-MHz frequencies.
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 GaN pulse generator circuit achieves efficient high-power ultrasound pulsing with reduced losses, enabling longer burst mode operation and higher frequencies, outperforming silicon-based systems in terms of power handling and efficiency.
Implementation Method 1
a first gate driver electrically coupled to a first GaN transistor and the first gate driver is configured to receive the signal from the transmitter beam former. Further, the system includes a second gate driver electrically coupled to a second GaN transistor
Implementation Method 2
each snubber circuit includes a respective capacitor and resistor, and each snubber circuit is configured to clamp a voltage overshoot when present
Implementation Method 3
each snubber circuit includes a respective capacitor and resistor, and each snubber circuit is configured to clamp a voltage overshoot when present
Implementation Method 4
The transformer is electrically connected downstream of the first GaN transistor, the second GaN transistor, the first snubber circuit, and the second snubber circuit. Furthermore, the transformer includes a plurality of windings in a center tapped configuration
Implementation Method 5
the transducer array generates ultrasound pulses in response to the output signal
Data Source
AI summary
An ultrasound pulse generator circuit includes a first gate driver electrically coupled to a first gallium nitride (GaN) transistor, a second gate driver electrically coupled to a second GaN transistor, a first snubber circuit, a second snubber circuit, and a transformer. The first snubber circuit and the second snubber circuit each include a respective capacitor and resistor and each snubber circuit is configured to clamp a voltage overshoot when present. Further, the transformer generates an output signal when operated and the third transformer is electrically connected downstream of the first GaN transistor, the second GaN transistor, the first snubber circuit, and the second snubber circuit. In addition, the transformer includes multiple windings.