Contributions a la faisabilite d'un systeme sur puce dedie a l'imagerie par ultrasons (French text)

Since its inception, medical imaging using ultrasonic equipment has been routinely employed in medical diagnosis. It is used to estimate the volume and the internal anatomy structure of the human body. The technique relies on ultrasonic beam propagation and echo detection. Nowadays, ultrasound imaging is widely used to evaluate, in a noninvasive way and in real-time, the internal anatomy structure and its function.; We present in this thesis a new design that integrates the digital part of the ultrasonic system on a chip. This integration will allow for the creation of a new generation of miniaturized and portable ultrasonic equipment. It will also make possible the visualization of ultrasound images in real time. Although a particular application (diagnostics using a 5 MHz probe) is described in this thesis, the suggested system could be useful in many other applications that require other frequencies.; The proposed ultrasonic system is composed of the following blocs. Firstly, an analog and radio-frequency bloc that includes a front-end amplifier, analog-to-digital conversion, a high-voltage emitter and a wireless transceiver. It is covered by the work of 3 master and Ph.D. students from our PolySTIM team. Secondly, a digital block which serves to construct the received ultrasonic images. It is based on the following building blocks: (1) Beamforming to form the received image pixel; (2) AM demodulation module, a low pass filter and a magnitude detection of the received signal; (3) Scan conversion to prepare the image for display; (4) Compression and display of the examined image.; The digital bloc, with the esception of the final display stage, is the subject of this work. More precisely, the contributions of this thesis are: (1) A new design method to evaluate the variable delay and determine the corresponding number of necessary registers used for each channel. We also propose an efficient pipeline architecture dedicated to implement these variable delays. Moreover, the resulting block is composed of a dedicated controller based on a simplified counter, a comparator, a demodulator, and a low-pass filter. (2) A new modified interpolation method to increase the resolution and reduce the artifacts on the far field of ultrasonic images. This method uses the nearest neighbor interpolation between two scan lines to produce two interpolated lines; a new third line is produced by using the linear interpolation between the two interpolated lines.; These two contributions were validated experimentally and will allow increasing the resolution of ultrasound images generated in real-time. (Abstract shortened by UMI.)...