A reconfigurable arbitrary waveform generator using PWM modulation for ultrasound research

BioMedical Engineering OnLine

Amauri A Assef¹  Joaquim M Maia¹  Fábio K Schneider¹  Vera LSN Button²  Eduardo T Costa² 

[1] Electrical/Electronic Engineering Department and the Graduate School of Electrical Engineering and Applied Computer Sciences (DAELT – DAELN – CPGEI), Federal University of Technology – Paraná (UTFPR), Curitiba, PR, Brazil

[2] Biomedical Engineering Department of the School of Electrical and Computer Engineering (DEB/FEEC) and Biomedical Engineering Centre (CEB), University of Campinas (UNICAMP), Campinas, SP, Brazil

关键词: Transmit beamformer;    Arbitrary waveform generator;    FPGA;    Ultrasound;   

Others  :  797917
DOI  :  10.1186/1475-925X-12-24

 received in 2012-12-17, accepted in 2013-03-12,  发布年份 2013

【 摘 要 】

Background

In ultrasound imaging systems, the digital transmit beamformer is a critical module that generates accurate control over several transmission parameters. However, such transmit front-end module is not typically accessible to ultrasound researchers. To overcome this difficulty, we have been developing a compact and fully programmable digital transmit system using the pulse-width modulation (PWM) technique for generating simultaneous arbitrary waveforms, specifically designed for research purposes.

Methods

In this paper we present a reconfigurable arbitrary waveform generator (RAWG) for ultrasound research applications that exploits a high frequency PWM scheme implemented in a low-cost FPGA, taking advantage of its flexibility and parallel processing capability for independent controlling of multiple transmission parameters. The 8-channel platform consists of a FPGA-based development board including an USB 2.0 interface and an arbitrary waveform generator board with eight MD2130 beamformer source drivers for individual control of waveform, amplitude apodization, phase angle and time delay trigger.

Results

To evaluate the efficiency of our system, we used equivalent RC loads (1 kΩ and 220 pF) to produce arbitrary excitation waveforms with the Gaussian and Tukey profiles. The PWM carrier frequency was set at 160 MHz featuring high resolution while keeping a minimum time delay of 3.125 ns between pulses to enable the acoustic beam to be focused and/or steered electronically. Preliminary experimental results show that the RAWG can produce complex arbitrary pulses with amplitude over 100 Vpp and central frequency up to 20 MHz with satisfactory linearity of the amplitude apodization, as well as focusing phase adjustment capability with angular resolution of 7.5°.

Conclusions

The initial results of this study showed that the proposed research system is suitable for generating simultaneous arbitrary waveforms, providing extensive user control with direct digital access to the various transmission parameters needed to explore alternative ultrasound transmission techniques.

【 授权许可】

   
2013 Assef et al.; licensee BioMed Central Ltd.

【 图 表 】

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