Octal LNA/VGA/AAF/ADC and CW I/Q Demodulator

The AD9279 is designed for low cost, low power, small size, and ease of use for medical ultrasound and automotive radar. It contains eight channels of a variable gain amplifier (VGA) with a low noise preamplifier (LNA), an antialiasing filter (AAF), an analog-to-digital converter (ADC), and an I/Q demodulator with programmable phase rotation.

Each channel features a variable gain range of 45 dB, a fully differential signal path, an active input preamplifier termination, and a maximum gain of up to 52 dB. The channel is optimized for high dynamic performance and low power in applications where a small package size is critical.

The LNA has a single-ended-to-differential gain that is selectable through the SPI. Assuming a 15 MHz noise bandwidth (NBW) and a 21.3 dB LNA gain, the LNA input SNR is roughly 94 dB. In CW Doppler mode, each LNA output drives an I/Q demod-ulator that has independently programmable phase rotation with 16 phase settings.

Power-down of individual channels is supported to increase battery life for portable applications. Standby mode allows quick power-up for power cycling. In CW Doppler operation, the VGA, AAF, and ADC are powered down. The ADC contains several features designed to maximize flexibility and minimize system cost, such as a programmable clock, data alignment, and programmable digital test pattern generation. The digital test patterns include built-in fixed patterns, built-in pseudo random patterns, and custom user-defined test patterns entered via the serial port interface.

* Lowpower : 141 mW per channel, TGC mode, 40 MSPS;

60 mW per channel, CW mode

* 10 mm × 10 mm, 144-ball CSP-BGA

* TGC channel input-referred noise: 0.8 nV/√Hz, max gain

* Flexible power-down modes

* Fast recovery from low power standby mode: <2us

* Overload recovery: <10 ns