AD9272 Octal LNA/VGA/AAF/ADC and Crosspoint Switch

ADI's AD9272 is designed for low cost, low power, small size, and ease of use. It contains eight channels of a low noise preamplifier (LNA) with a variable gain amplifier (VGA); an antialiasing filter (AAF); and a 12-bit, 10 MSPS to 80 MSPS analog-to-digital converter (ADC).

Each channel features a variable gain range of 42 dB, a fully differential signal path, an active input preamplifier termination, a maximum gain of up to 52 dB, and an ADC with a conversion rate of up to 80 MSPS. The channel is optimized for 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. The LNA input-referred noise voltage is typically 0.75 nV/√Hz at a gain of 21.3 dB, and the combined input-referred noise voltage of the entire channel is 0.85 nV/√Hz at maximum gain. Assuming a 15 MHz noise bandwidth (NBW) and a 21.3 dB LNA gain, the input SNR is about 92 dB. In CW Doppler mode, the LNA output drives a transconductance amp that is switched through an 8 x 8 differential crosspoint switch. The switch is programmable through the SPI.