Industry's first octal ultrasound receiver reduces processor overhead

July 23, 2012 // By Nick Flaherty
Analog Devices has introduced the industry’s first octal ultrasound receiver with on-chip digital I/Q demodulation and decimation filtering.

With embedded demodulation and decimation, the AD9670 is the first ultrasound receiver able to condition eight channels of data from RF to a baseband frequency, reducing the processing load on the system FPGA (field-programmable gate array) by at least 50 percent compared to other receivers. The AD9670 also integrates a low-noise amplifier, variable gain amplifier, anti-aliasing filter, and a 14-bit, A/D converter with the industry’s highest sample rate (125 MSPS) and best SNR (signal-to-noise ratio) performance (75 dB) for enhanced ultrasound image quality. The new octal receiver is the latest addition to Analog Devices’ award winning ultrasound receiver portfolio and is designed for mid- to high-end portable and cart-based ultrasound systems.
The integrated digital I/Q demodulator, programmable-oscillator and 16-tap FIR (finite-impulse response) decimation filter of the AD9670 reduce the FPGA’s data bandwidth requirements, allowing designers to use less expensive processors or reallocate processing bandwidth to other system functions. The new receiver also provides a continuous wave (CW) processing path with an analog I/Q demodulator that has harmonic rejection to the 13th order, which allows designers to reduce the number of filter components to lower system cost, reduce design complexity, and improve signal sensitivity. The CW-mode output dynamic range is more than 160 dBc/ √Hz per channel.
Additionally, the AD9670 octal receiver’s 30-MHz anti-aliasing filter frequency and 125-MSPS A/D converter sample rate combine to yield SNR performance that is 3-dB higher than competing devices. The 14-bit A/D converter also features a programmable clock, data alignment, and programmable digital test pattern generation, including built-in fixed and pseudo random patterns and custom user-defined test patterns, entered via a serial port interface. Total power is 130-mW per channel, while an eight-channel low-noise amplifier reduces input-referred noise to just 0.78 nV/√Hz typical at 5 MHz (gain = 21.3 dB).
“By introducing the first octal ultrasound receiver with digital demodulation and decimation filtering, we are able to minimize the data I/O and throughput rates and place