Analog Devices has introduced a new IC that, it claims, simplifies the development of continuous wave (CW) Doppler imaging in stationary and portable ultrasound systems.
CW Doppler is an advanced Doppler technique, used in approximately 30% of today’s cardiac ultrasound equipment that allows physicians to accurately assess the physical state of arteries, veins and blood vessels by quickly detecting blood flow and direction.
CW Doppler ultrasound systems require analog beam forming (ABF) because the large dynamic range cannot be processed digitally. Historically, an ABF front-end consisted of multiple low-noise amplifiers, analog delay lines, and numerous cross-point switch matrices.
The dual-channel AD8333 alters this approach by replacing it with a programmable phase-shifting technique with an I/Q demodulator for each input channel, eliminating the need for multiple analog delay lines and cross-point switches.
The monolithic device achieves a dynamic range of 161 dB/Hz, which is equal to or exceeds the dynamic range of existing multi-chip solutions, while using less than 25% of the board space per channel and delivering a per-channel bill of materials savings of up to 75%.
The AD8333 is designed with 22.5 degree phase steps, allowing for accurate time alignment of multiple channels in continuous wave beam forming applications. The amplifier offers parallel 4-bit digital control of phase states, and provides accurate channel matching through a common LO interface.
Analog Devices offers a suite of products to complement the AD8333 and help customers complete the design of their medical ultrasound systems, including the AD8332 dual variable gain amplifier (VGA) or the AD8335 quad VGA, the AD9510 clock IC, the AD8021 high-speed amp and AD8016 line driver, and either the AD7665, AD7679, or AD7685 members of ADI’s PulSAR family of analog-to-digital converters.
While the power budget and board and cost savings enabled by the AD8333 optimize the development of advanced CW Doppler ultrasound equipment for both fixed and portable medical environments, the combination of I/Q demodulation and phase shifting also suits the AD8333 to other applications where measurement of phase shifts are required, including weather radar, adaptive antenna arrays, and automotive collision avoidance systems.
The AD8333 monolithic Doppler phase-shifter is currently sampling and will be in full production in August 2005.