ABSTRACT
Recently, a method was proposed to determine the parameters for each Class DE driver in high-intensity focused ultrasound arrays for efficient operation and to compensate for variations in the impedance of each array element. This work extends that method to consider the effect of switch resistance and to provide limited control on the power delivered to the transducers with a constant supply voltage while keeping a good efficiency. The method is experimentally validated using an integrated driver developed by the authors. This paper also shows that the frequency range for efficient electrical operation is close to the frequency where the transducer array presents a peak in the conversion efficiency.
Subject(s)
Amplifiers, Electronic , High-Intensity Focused Ultrasound Ablation/instrumentation , Transducers , Acoustics , Computer Simulation , Electric Impedance , Image Processing, Computer-Assisted , Magnetic Resonance Imaging , Wavelet AnalysisABSTRACT
This paper presents a practical implementation of an integrated MRI-compatible CMOS amplifier capable of directly driving a piezoelectric ultrasound transducer suitable for high-intensity focused ultrasound (HIFU) therapy. The amplifier operates in Class DE mode without the need for an output matching network. The integrated amplifier has been implemented with the AMS AG H35 CMOS process. A class DE amplifier design methodology for driving unmatched piezoelectric loads is presented along with simulation and experimental results. The proposed design achieves approximately 90% efficiency with over 800 mW of output power at 1010 kHz. The total die area including pads is 2 mm(2). Compatibility with MRI was validated with B1 imaging of a phantom and the amplifier circuit.
