Circuit design and simulation of a transmit beamforming ASIC for high-frequency ultrasonic imaging systems

This paper describes the design of a programmable transmit beamformer application-specific integrated circuit (ASIC) with 8 channels for ultrasound imaging systems. The system uses a 20-MHz reference clock. A digital delay-locked loop (DLL) was designed with 50 variable delay elements, each of which...

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Bibliographic Details
Published in:IEEE transactions on ultrasonics, ferroelectrics, and frequency control ferroelectrics, and frequency control, 2011-07, Vol.58 (7), p.1320-1331
Main Authors: Athanasopoulos, G. I., Carey, S. J., Hatfield, J. V.
Format: Article
Language:English
Subjects:
Acoustic signal processing
Acoustics
Channels
Circuit design
Clocks
Control theory
Delay
Detectors
Dynamic link libraries
Equipment Design
Exact sciences and technology
Feedback
Fundamental areas of phenomenology (including applications)
Image edge detection
Imaging
Physics
Signal Processing, Computer-Assisted
Transducers
Transduction
acoustical devices for the generation and reproduction of sound
Transistors
Ultrasonography - instrumentation
Voltage control
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Summary:This paper describes the design of a programmable transmit beamformer application-specific integrated circuit (ASIC) with 8 channels for ultrasound imaging systems. The system uses a 20-MHz reference clock. A digital delay-locked loop (DLL) was designed with 50 variable delay elements, each of which provides a clock with different phase from a single reference. Two phase detectors compare the phase difference of the reference clock with the feedback clock, adjusting the delay of the delay elements to bring the feedback clock signal in phase with the reference clock signal. Two independent control voltages for the delay elements ensure that the mark space ratio of the pulses remain at 50%. By combining a 10- bit asynchronous counter with the delays from the DLL, each channel can be programmed to give a maximum time delay of 51 μs with 1 ns resolution. It can also give bursts of up to 64 pulses. Finally, for a single pulse, it can adjust the pulse width between 9 ns and 100 ns by controlling the current flowing through a capacitor in a one-shot circuit, for use with 40-MHz and 5-MHz transducers, respectively.
ISSN:0885-3010
1525-8955
DOI:10.1109/TUFFC.2011.1952