5 – 14 HS40 Service Manual
5.4.2.2. Description
■ Transmit Channel
The Transmit Channel function applies a high voltage signal to the probe element to
generate ultrasound waves. It generates a high voltage pulse to transmit arbitrary waveforms
from the BF FPGA.
The Transmit Part consists of the BF FPGA and the Pulser.
① BF FPGA
The BF FPGA uses a RTC signal to calculate a delay time for TX focusing and fires a
pulse as an output to each TX channel.
② Pulser
The Pulser amplifies the Firing Pulse input signal into a high voltage output signal that is
sent to each probe element. As a result, the probes vibrate and generate ultrasound.
■ Receive Channel
The Receive Channel amplifies the echoes reflected from the human body. This signal is
converted from analog to digital for beamforming by the BF FPGA. The BF FPGA focuses
the signals from each channel and sends them to the BE Board. The Receive Part consists
of TR Switch, AFE, and BF FPGA.
① TR Switch
Each probe element is connected in parallel to the TX Channel and the RX Channel. Up
to 180 Vpp Tx Pulse and mV-range Echo signals are mixed with each other. The RX data
is required to be an echo signal in the mV range, which is very weak signal. The TR
Switch prevents the high-voltage Tx Pulse from flowing into the AFE input, but permits
low-level echo signals to pass.
② AFE
HS40 uses an all-in-one type AFE. One AFE performs the roles of LNA, TGC, and ADC
for existing equipment. The AFE amplifies the mV-range echo input signal and performs
gain compensation over time. It also transmits the digitized RX Data to the BF FPGA.
③ BFX FPGA
The BF FPGA performs RX focusing for each RX Channel data received from the AFE
and combines the whole channel data. Then, it transmits the summed data to the BE
Board.
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