Overview

Features and Benefits

  • 11-bit, 250 MSPS output data rate per channel
  • Performance with NSR enabled
    • SNR: 74.5 dBFS in a 55 MHz band to 90 MHz at 250 MSPS
    • SNR: 72.0 dBFS in a 82 MHz band to 90 MHz at 250 MSPS
  • Performance with NSR disabled
    • SNR: 66.2 dBFS up to 90 MHz at 250 MSPS
    • SFDR: 85 dBc up to 185 MHz at 250 MSPS
  • Total power consumption: 706 mW at 200 MSPS
  • 1.8 V supply voltages
  • LVDS (ANSI-644 levels) outputs
  • Integer 1-to-8 input clock divider (625 MHz maximum input)
  • Internal ADC voltage reference
  • Flexible analog input range
    • 1.4 V p-p to 2.0 V p-p (1.75 V p-p nominal)
  • Differential analog inputs with 400 MHz bandwidth
  • 95 dB channel isolation/crosstalk
  • Serial port control
  • Energy saving power-down modes

Product Details

The AD6643 is an 11-bit, 200 MSPS/250 MSPS, dual-channel intermediate frequency (IF) receiver specifically designed to support multi-antenna systems in telecommunication applications where high dynamic range performance, low power, and small size are desired.

The device consists of two high performance analog-to-digital converters (ADCs) and noise shaping requantizer (NSR) digital blocks. Each ADC consists of a multistage, differential pipelined architecture with integrated output error correction logic, and each ADC features a wide bandwidth switched capacitor sampling network within the first stage of the differential pipeline. An integrated voltage reference eases design considerations. A duty cycle stabilizer (DCS) compensates for variations in the ADC clock duty cycle, allowing the converters to maintain excellent performance.

Each ADC output is connected internally to an NSR block. The integrated NSR circuitry allows for improved SNR performance in a smaller frequency band within the Nyquist bandwidth. The device supports two different output modes selectable via the SPI. With the NSR feature enabled, the outputs of the ADCs are processed such that the AD6643 supports enhanced SNR performance within a limited portion of the Nyquist bandwidth while maintaining an 11-bit output resolution.

The NSR block can be programmed to provide a bandwidth of either 22% or 33% of the sample clock. For example, with a sample clock rate of 185 MSPS, the AD6643 can achieve up to 75.5 dBFS SNR for a 40 MHz bandwidth in the 22% mode and up to 73.7 dBFS SNR for a 60 MHz bandwidth in the 33% mode.

When the NSR block is disabled, the ADC data is provided directly to the output at a resolution of 11 bits. The AD6643 can achieve up to 66.5 dBFS SNR for the entire Nyquist bandwidth when operated in this mode. This allows the AD6643 to be used in telecommunication applications such as a digital predistortion observation path where wider bandwidths are required.

After digital signal processing, multiplexed output data is routed into an 11-bit output port such that the maximum data rate is 400 Mbps (DDR). These outputs are LVDS and support ANSI-644 levels.

The AD6643 receiver digitizes a wide spectrum of IF frequencies. Each receiver is designed for simultaneous reception of a separate antenna. This IF sampling architecture greatly reduces compo-nent cost and complexity compared with traditional analog techniques or less integrated digital methods.

Flexible power-down options allow significant power savings. Programming for device setup and control is accomplished using a 3-wire SPI-compatible serial interface with numerous modes to support board level system testing.

The AD6643 is available in a Pb-free, RoHS-compliant, 64-lead, 9 mm × 9 mm lead frame chip scale package (LFCSP_VQ) and is specified over the industrial temperature range of −40°C to +85°C. This product is protected by a U.S. patent.

Product Highlights

  1. Two ADCs are contained in a small, space-saving, 9 mm × 9 mm × 0.85 mm, 64-lead LFCSP package.
  2. Pin selectable noise shaping requantizer (NSR) function that allows for improved SNR within a reduced bandwidth of up to 60 MHz at 185 MSPS.
  3. LVDS digital output interface configured for low cost FPGA families.
  4. Operation from a single 1.8 V supply.
  5. Standard serial port interface (SPI) that supports various product features and functions, such as data formatting (offset binary or twos complement), NSR, power-down, test modes, and voltage reference mode.
  6. On-chip integer 1-to-8 input clock divider and multichip sync function to support a wide range of clocking schemes and multichannel subsystems.

Applications

  • Communications
  • Diversity radio and smart antenna (MIMO) systems
  • Multimode digital receivers (3G)
    • WCDMA, LTE, CDMA2000
    • WiMAX, TD-SCDMA
  • I/Q demodulation systems
  • General-purpose software radios

Product Lifecycle icon-recommended 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)

Documentation

Tools & Simulations

Virtual Eval - BETA

Virtual Eval is a web application to assist designers in product evaluation of ADCs, DACs, and other ADI products. Using detailed models on Analog’s servers, Virtual Eval simulates crucial part performance characteristics within seconds. Configure operating conditions such as input tones and external jitter, as well as device features like gain or digital down-conversion. Performance characteristics include noise, distortion, and resolution, FFTs, timing diagrams, response plots, and more.

VirtualEval

IBIS Models

AD6643 IBIS Model

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.

ADIsimRF

ADIsimRF is an easy-to-use RF signal chain calculator. Cascaded gain, noise, distortion and power consumption can be calculated, plotted and exported for signal chains with up to 50 stages. ADIsimRF also includes an extensive data base of device models for ADI’s RF and mixed signal components.

Product Recommendations

AD6643 Companion Parts

Recommended Clock Drivers

Recommended Driver Amplifiers

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.