Datasheet

AD9277
Rev. 0 | Page 3 of 48
GENERAL DESCRIPTION
The AD9277 is designed for low cost, low power, small size,
and ease of use. It contains eight channels of a variable gain
amplifier (VGA) with a low noise preamplifier (LNA); an anti-
aliasing filter (AAF); a 14-bit, 10 MSPS to 50 MSPS analog-to-
digital converter (ADC); and an I/Q demodulator with
programmable phase rotation.
Each channel features a variable gain range of 42 dB, a fully differ-
ential 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 50 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 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 0.85 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 inde-
pendently programmable phase rotation through the SPI with
16 phase settings.
The AD9277 requires a LVPECL-/CMOS-/LVDS-compatible
sample rate clock for full performance operation. No external
reference or driver components are required for many applications.
The ADC automatically multiplies the sample rate clock for
the appropriate LVDS serial data rate. A data clock (DCO±) for
capturing data on the output and a frame clock (FCO±) trigger
for signaling a new output byte are provided.
Powering down individual channels is supported to increase
battery life for portable applications. A standby mode option
allows quick power-up for power cycling. In CW Doppler opera-
tion, the VGA, AAF, and ADC are powered down. The power of
the TGC path scales with selectable ADC speed power modes.
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.
Fabricated in an advanced CMOS process, the AD9277 is
available in a 16 mm × 16 mm, RoHS compliant, 100-lead
TQFP. It is specified over the industrial temperature range
of −40°C to +85°C.