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Feature
Product Name: | SMD LED PCB Board |
Used for: | SMT FACTORY Electronic Circuit Board |
Warranty: | 1 Year |
Shipment | by air |
Delivery Time: | 1-2Days |
Our Main Market | Whole of the world |
Application
Converter editor
A high-speed analog-to-digital converter (ADC) is usually the most
basic component of an analog front-end PCB circuit system. Since
the performance of the analog/digital meta converter determines the
overall performance of the system, system manufacturers often
regard the analog/digital converter as the most important
component. This article will explain in detail the operation
principle of the front end of the ultrasound system, and
specifically discuss the role of the analog/digital converter in
it.
When PCB design the front-end PCB circuit of the ultrasound system,
manufacturers must carefully consider several important factors in
order to make proper trade-offs. Whether the medical staff can make
the correct diagnosis depends on the critical role of the analog
PCB circuit in this process.
The performance of an analog PCB circuit depends on many different
parameters, including crosstalk between channels,
spurious-free-signal dynamic range (SFDR), and total harmonic
distortion. Therefore, manufacturers must consider these parameters
in detail before deciding which analog PCB circuit to use.
Taking an analog/digital converter as an example, if an advanced
PCB circuit such as a serial LVDS driver is added, the PCB circuit
board can be reduced, and noise interference such as
electromagnetic waves can be suppressed, which helps to further
improve the PCB design of the system. The manufacture of
miniaturized, high-performance and full-featured ultrasound system
products has caused the market to continue to demand the production
of low-power analog ICs with better integration with amplifiers,
analog/digital converters, and small packages.
System Overview
The ultrasound imaging system is currently the most commonly used
and most sophisticated signal processing instrument, and can assist
medical personnel in making a correct diagnosis. At the front end
of the ultrasound system, extremely precise analog signals are used
to process PCB circuits such as analog/digital converters and low
noise amplifiers (LNAs). The performance of these analog PCB
circuits is a key factor in determining system performance.
Ultrasonic devices are very close to radar or sonar systems, but
operate in different frequency bands (ranges). The radar operates
in the GHz (gigahertz) range, sonar in the kHz (kHz) range, and the
ultrasound system operates in the MHz (megahertz) range. The
principle of these devices is almost the same as that of the array
antenna radar system used in commercial and military aircraft. The
PCB designers of radar systems use the principle of phased steering
beamformer arrays, which were later adopted by the ultrasound
system PCB designer and improved.
In all ultrasonic system instruments, there is a multiplex
converter at the end of a relatively long cable (about 2 meters).
The cable contains up to 256 micro-coaxial cables and is one of the
most expensive components in an ultrasonic system. Ultrasound
systems are generally equipped with a number of different
transducer probes so that the medical staff responsible for the
operation can select the appropriate transducer depending on the
field requirements of the scanned image.
Image production
In the first step of the scanning process, each converter is
responsible for generating a pulse signal and transmitting the
signal. The transmitted pulse signal passes through the human body
tissue in the form of high-frequency sound waves. The transmission
speed of the sound waves is generally between 1 and 20 MHz. These
pulse signals start timing and calibration detection in the human
body. When the signal passes through the body tissue, some of the
sound waves will be reflected back to the converter module, and the
converter is responsible for detecting the potential of these
echoes (after the converter sends the signal out, it will switch
immediately and switch to receive mode). The strength of the echo
signal depends on the position of the echo signal reflection point
in the human body. The signal reflected directly from the
subcutaneous tissue is generally very strong, and the signal
reflected from the deep part of the human body is very weak.
Since health and safety laws are dictated by the maximum amount of
radiation the human body can withstand, the electronic receiving
system designed by the engineer PCB must be extremely sensitive. In
the area of illness close to the human epidermis, we call it the
near field, and the reflected energy is high. However, if the
disease area is in a deep part of the human body, which is called
the far field, the echo received will be extremely weak and must
therefore be amplified 1000 times or more.
In the far-field image mode, its performance limit comes from all
the noise present in the receiving link. The converter/cable
assembly and the receiver system's low-noise amplifier are the two
largest sources of extraneous noise. In the near-field video mode,
the performance limitation comes from the size of the input signal.
The ratio between these two signals determines the dynamic range of
the ultrasonic instrument.
Through a series of receivers such as time phase conversion,
amplitude adjustment, and intelligent cumulative echo energy, it is
possible to obtain high-definition images. Using the time shift of
the converter array and adjusting the amplitude of the received
signal can make the device have the function of fixed-point
observation of the scanning position. After serialized observations
of different parts of the site, ultrasonic instruments can create a
combined image.
Digital wave can complete the combination of signals. In a digital
wave, echo pulse signals that are reflected from a point in the
body are stored in each channel first, then arranged in order of
priority, and fixed in a homonymous signal, and then gathered. This
process of aggregating the outputs of multiple analog/digital
converters can increase the gain because the noise within the
channel is not related to each other. (Note: The analog
wave-forming technique has basically become an outdated method, and
most of the modern ones use digital wave-forming). The image is
formed by sampling the simulation layer closest to the converter
system, storing it, and digitizing them together.
The DBF system requires precise channel and channel matching. Both
channels require VGA (video graphics array), and this will continue
until the A/D converter device is large enough to handle the large
dynamic range and can provide reasonable cost and low power
consumption.
Image mode
1. Grayscale image -- produces basic black and white images
The image will be discriminated into units as small as 1mm, and the
image will be rendered by emitting energy and detecting those
returned energy (as previously described).
2. Doppler (Doppler) - Doppler mode is used to detect the velocity
of objects moving in various environments by tracking the frequency
offset of echoes. These principles are applied to examine the flow
of blood or other fluids in the body. This technique is to launch a
series of sound waves into the body and then perform a fast Fourier
transform (FFT) on the reflected waves. This calculation and
processing method can determine the signal frequency components
from the human body and their relationship with the fluid velocity.
3. Vein and Arterial Patterns - This method is a combination of
Doppler images and grayscale patterns. The rate and rhythm can be
obtained by processing the audio signal generated by the Doppler
shift.