A new eight-channel ultrasound receiver features on-chip digital I/Q demodulation, programmable oscillator, and decimation filtering. The AD9670 from Analog Devices Inc. conditions eight channels of data from RF to a baseband frequency, easing the FPGA processing burden in cart-based and portable ultrasound equipment. The receiver also provides a continuous wave (CW) processing path with an analog I/Q demodulator that has harmonic rejection to the 13th order, allowing 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/ Hz1/2 per channel.
The device integrates a variable-gain amplifier, a 30-MHz anti-aliasing filter, and a 14-bit A/D converter with a sample rate of 125 MSPS and SNR performance of 75 dB for enhanced ultrasound image quality. The converter also includes a programmable clock and data alignment. Programmable digital test pattern generation provides built-in fixed and pseudo random patterns and custom user-defined test patterns, entered via a serial port interface. In addition, an amplifier reduces input-referred noise to 0.78 nV/Hz1/2 typical at 5 MHz (gain = 21.3 dB).
Additional features include:
FIR decimation filter - 16 taps per decimation factor - Maximum decimation of 32
8-channel LNA, VGA, AAF, ADC
Power usage - 130-mW/channel @ 40 MSPS in TGC (time gain compensation) mode - 55 mW/channel in CW mode
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