Development of a modular FPGA based digital beamformer for PC based ultrasound imaging system

A digital transmit and receive beamformer for
PC based ultrasound imaging was developed. This system
consists of an analog front end, FPGA control board,
ultrasound probe, and computer. Analog front end consists of
programmable pulser and receiver circuit. The pulser circuit
uses high voltage pulse generator to produce monocycle
electrical pulses with the adjustable center frequency and
amplitude up to 50 V. The receiver circuit uses a AD9272
chip, which is an 8-channel integrated analog front end
module. Each of the 8 signal paths consists of a low noise
amplifier (LNA), a digitally programmable variable gain
amplifier (VGA), anti aliasing filter (AAF), and a 12-bit, 40
Mega Samples Per Second (MSPS) analog-to-digital converter
(ADC). The probe is a 64 element linear probe which can
produce pulses with center frequency of 3.5 MHz. The Xillinx
Spartan 6 FPGA based beamformer consists of 8 channel
transmit beamformer controller block and 8 channel receive
beamformer blocks. The receive beamformer is composed with
delay stage block, apodization blok, summation block, Hilber
transform block, and envelope detection block. The
implementation result shows that the system was able to
process the RF signals.