18 Service Manual
3 Principle Descriptions
3.2.2 VBF Board
VBF board is an ultrasound signal processing board, used to control the transmit and acquisition of
ultrasound beam, perform the relevant post processing.
Echo Singal
Transmit
Stimulus
Beam Coumpound
& Control (FPGA)
Transception
Switch
Singal
Amplification
& AD
Figure 3-5 VBF Board Diagram
The echo signal acquired by AD (AFE5808) is transmitted to FPGA, accomplishes beam compound
and dynamic focusing in FPGA, the processed echo signal is finally transmitted to the ultrasound
system, thereafter, the signal becomes one received ultrasound beam. The transmit stimulus is
provided and controlled by FPGA. The transception switch (MAX4936) is used to isolate transmit
stimulus from echo signal, i.e. identifying transmit stimulus to be high-voltage signal and echo signal
to be small signal. The recurring signal processing produces a ultrasound image, and displays it on
the monitor.
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