Medical imaging machines send complex signals into the body, then receive and process the signal reflections to develop an image of the internal body organs, blood flow or bone structure. Our high-performance signal-chain components drive imaging transducers that send and receive imaging signals to produce high-resolution images for improved diagnosis and treatment.
By transmitting acoustic energy into the body and receiving and processing the signal reflections, phased-array ultrasound systems can generate images of internal organs and structures, map blood flow and tissue motion, and provide highly accurate blood velocity information.
Historically, the large number of high-performance phased-array transmitters and receivers required to implement these imaging systems resulted in large and expensive cart-based implementations. Recently, advances in integration have empowered system designers to migrate to smaller, lower cost, and more portable imaging solutions with performance approaching that of the larger systems.
The challenge going forward is to continue to drive the integration of these solutions into smaller form factors, while increasing their performance and diagnostic capabilities.
The MRI transmitter generates the RF pulses necessary to resonate the hydrogen nuclei. The range of frequencies in the transmit excitation pulse and the magnitude of the gradient field determine the width of the image slice. A typical transmit pulse will produce an output signal with a relatively narrow ±1kHz bandwidth. The time-domain waveform required to produce this narrow frequency band typically resembles a traditional sync function. This waveform is usually generated digitally at baseband and then up converted by a mixer to the appropriate center frequency. Traditional transmit implementations require relatively low-speed, digital-to-analog converters (DACs) to generate the baseband waveform, as the bandwidth of this signal is relatively small.
Advances in DAC technology have made other potential transmit architectures achievable. Very high-speed, high-resolution DACs can be utilized for direct RF generation of transmit pulses up to 300MHz. Waveform generation and up-conversion over a broad band of frequencies can now be accomplished in the digital domain.
An RF receiver is used to process the signals from the receiver coils. Most modern MRI systems have six or more receivers to process the signals ranging from approximately 1MHz to 300MHz, with the frequency range highly dependent on applied static magnetic field strength. The bandwidth of the received signal is small, typically less than 20kHz, and dependent on the magnitude of the gradient field. A traditional MRI receiver configuration has a low-noise amplifier (LNA) followed by a mixer. The mixer mixes the signal of interest to a low-frequency IF frequency for conversion by a high-resolution, low-speed, analog-to digital converter (ADC). In this receive architecture, the ADCs have relatively low sample rates below 1MHz. Because of the low-bandwidth requirements, ADCs with higher, 1MHz to 5MHz, sample rates can be used to convert multiple channels by time-multiplexing the receive channels through an analog multiplexer into a single ADC.
With the advent of higher performance ADCs, newer receiver architectures are now possible. High-input-bandwidth, high resolution, ADCs with sample rates up to 100MHz can also be used to directly sample the signals, thereby eliminating the need for analog mixers in the receive chain.
This octal, three-level, digital pulser generates high-frequency, HV bipolar pulses (up to ±105V) from low-voltage control logic inputs for driving piezoelectric transducers in ultrasound systems.
This octal, high-voltage, transmit/receive (T/R) switches is based on a diode bridge topology and features . The amount of current in the diode bridges can be programmed through an SPI™ interface.
This fully-integrated octal ultrasound transceiver is optimized for high channel-count, high-performance portable and cart-based ultrasound systems. This transceiver allows the user to achieve high-end 2D and Doppler imaging capability using substantially less space and power.
A fully integrated octal ultrasound receiver is optimized for high channel count, high-performance portable and cart-based ultrasound systems.
Our medical imaging solutions provide additional information on designing medical imaging products, including examples and block diagrams of typical designs.
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