Analog Devices Inc. has announced the third generation of its octal receiver ICs for use in Doppler ultrasound applications, such as ultrasonic imaging systems. Designed for use in systems operating in continuous-wave or pulsed Doppler mode, the AD9276 and AD9277 octal ultrasound receivers integrate gain, filtering, data conversion, and demodulation for Doppler signal processing in a single chip.
The AD9277 and AD9277 octal ultrasound receivers provides eight signal channels optimized for dynamic performance and low power in applications where a small package size is critical.
Each channel has a signal processing string consisting of a variable-gain amplifier (VGA), low-noise preamplifier (LNA), anti-aliasing filter (AAF), analog-to-digital converter (ADC), and I/Q demodulator. Each channel has a variable gain range of 42 dB, a fully differential signal path, an active input preamplifier termination, and maximum gain of up to 52 dB. The AD9277 has a 14-bit, 50-MSPS ADCs, while the AD9276 has 12-bit, 80-MSPS ADCs .
The single-ended-to-differential gain of the LNA is selectable via the SPI port. The LNA input noise is typically 0.75 nV/√Hz at a gain of 21.3 dB, and the combined input-referred noise of the entire channel is 0.82 nV/√Hz at maximum gain. Assuming a 15-MHz noise bandwidth (NBW) and a 21.3-dB LNA gain, the input SNR is roughly 92 dB. In CW Doppler mode, each LNA output drives an I & Q demodulator. Each demodulator has independently programmable phase rotation with 16 phase settings.
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