This paper presents the development of a digital beamformer transmitter system for generation of arbitrary ultrasound waveforms, specifically designed for research purposes. The proposed architecture has 8 independent excitation channels and uses an FPGA device (Field Programmable Gated Array) for electronic control channel generation of ultrasonic acoustic beam transmission. The system allows operation in pulse-echo mode, with pulse repetition rate of excitation between 62.5 Hz and 8 kHz, or single pulse, center frequency between 500 kHz and 20 MHz, excitation voltage between -100 and +100 V, and individual control of amplitude apodization, phase angle and time delay trigger. The mathematical method for determining the digital signals of excitation is presented and validated through practical results for waveform generation with Gaussian profile and center frequency of 20 MHz, in a load formed by a 220 pF capacitor in parallel with a resistor of 1 k Ω. The results show that the proposed flexible and fully programmable architecture, can support the development of new algorithms and sophisticated processing techniques of the transmission beamformer.
Ultrasound; beamformer transmitter; arbitrary waveform; FPGA
