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AD9278: Octal LNA/VGA/AAF/ADC and CW I/Q Demodulator (Rev. A)11/1/2010PDF768 kB
Overview
Features and Benefits
8 CHANNELS OF LNA, VGA, AAF, ADC, AND I/Q DEMODULATOR
- Low power: 88 mW per channel, TGC mode, 40 MSPS;
32 mW per channel, CW mode - 10 mm × 10 mm, 144-ball CSP-BGA
- TGC channel input-referred noise: 1.3 nV/√Hz, max gain
- Flexible power-down modes
- Fast recovery from low power standby mode: <2 μs
- Overload recovery: <10 ns
- Input-referred noise: 1.25 nV/√Hz, gain = 21.3 dB
- Programmable gain: 15.6 dB/17.9 dB/21.3 dB
- 0.1 dB compression: 1000 mV p-p/750 mV p-p/450 mV p-p
- Dual-mode active input impedance matching
- Bandwidth (BW): >50 MHz
ANTIALIASING FILTER (AAF)
- Programmable second-order LPF from 8 MHz to 18 MHz
- Programmable HPF
- Attenuator range: −45 dB to 0 dB
- Postamp gain (PGA): 21 dB/24 dB/27 dB/30 dB
- Linear-in-dB gain control
- SNR: 70 dB, 12 bits up to 65 MSPS
- Serial LVDS (ANSI-644, low power/reduced signal)
- Individual programmable phase rotation
- Output dynamic range per channel: >158 dBc/√Hz
- Output-referred SNR: 153 dBc/√Hz, 1 kHz offset, −3dBFS
Product Details
The AD9278 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 12-bit, 10 MSPS to 65 MSPS 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, a maximum gain of up to 51 dB, and an ADC with a conversion rate of up to 65 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 1.3 nV/√Hz at a gain of 21.3 dB, and the combined input-referred noise of the entire channel is 1.3 nV/√Hz at maximum gain. Assuming a 15 MHz noise bandwidth (NBW) and a 21.3 dB LNA gain, the input SNR is roughly 88 dB. In CW Doppler mode, each LNA output drives an I/Q demodulator. Each demodulator has independently programmable phase rotation through the SPI with 16 phase settings.
The AD9278 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 operation, 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 BiCMOS process, the AD9278 is available in a 10 mm × 10 mm, RoHS compliant, 144-lead BGA. It is specified over the industrial temperature range of −40°C to +85°C.
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Recommended for New Designs
This product has been released to the market. The data sheet contains all final specifications and operating conditions. For new designs, ADI recommends utilization of these products.
Evaluation Kits (2)
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Design Tools
Visual Analog
For designers who are selecting or evaluating high speed ADCs, VisualAnalog™ is a software package that combines a powerful set of simulation and data analysis tools with a user-friendly graphical interface.
Product Recommendations
AD9278 Companion Parts
Recommended Clock Drivers
- For low jitter performance: AD9510, AD9511, AD9512, AD9513, AD9514, AD9515.
- For low jitter, low power, clock fanout buffers: ADCLK846, ADCLK946.
Recommended A/D Converter
- For sampling the I and Q signals in analog beamforming applications: AD7982.
Recommended Driver Amplifiers
- For I-to-V conversion and ADC driver in CW signal path: ADA4896-2, ADA4897-2.
Recommended Gain Control of VGA
Design Resources
ADI has always placed the highest emphasis on delivering products that meet the maximum levels of quality and reliability. We achieve this by incorporating quality and reliability checks in every scope of product and process design, and in the manufacturing process as well. "Zero defects" for shipped products is always our goal.
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Pricing displayed is based on 1-piece. The USA list pricing shown is for budgetary use only, shown in United States dollars (FOB USA per unit), and is subject to change. International prices may vary due to local duties, taxes, fees and exchange rates.