| Summary: | 碩士 === 長庚大學 === 電機工程學系 === 101 === Focused ultrasound technology has confirmed that has the therapeutic effect for biological tissues, and temporarily opens the blood-brain barrier and does the functions of the brain to carry out local drug delivery in recent years. At present, for thermal ablation purpose, the frequency range of the driving system typically higher than 0.5 MHz for better tissue absorption and rapid temperature increase. However, the above frequency range encounters severe bone absorption and focal beam distortion to make the transcranial ultrasound therapy becomes difficult. Recently we have already one prototype of the low-frequency, low skull absorption, 256-channel focused ultrasound phased array system for the purpose of local brain drug delivery. The system provides electrical focal steering within a wide area, as well as power monitoring for each channel output. Currently, the forward and reflect power monitoring can be achieved in the continuous model exposure. However, for a rather suitable burst-tone exposure as an output mode of the focused ultrasound system for brain drug delivery, the output of power focused ultrasound channels cannot be accurately estimated. The purpose of this thesis is to present the improvement of the power-sensor module design for the a 256-channel RF driving system, and provide special design uses voltage feedback and use of calculation of voltage signal output power and feedback circuit of the power system, to address the burst-tone power measurement, making it possible to monitor individual power output of the continuous mode and pulsed mode output.
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