JEFF’S PICKS: A-D Processing Board Family Boasts Scalable, Flexible Architecture
Jeff Child, Editor-in-Chief
Today’s military digital conversation applications rely heavily on analog-to-digital converters (ADCs), digital-to-analogy converters and FPGAs. The evolving trend in recent years is to perform digital conversion as soon along the signal chain as possible. High-bandwidth A/D converters with high sampling rates must connect to extremely fast data transfer paths to store and process data with triggering or gating circuitry to digitize pulse waveforms at precisely the right time. To feed those needs, board vendors continue to push the barriers with solutions with ever faster ADCs and more sophisticated FPGAs. A rich selection of digital receiver products combine ADCs and FPGAs on one VME, VPX, or PCI Express board. Other solutions pair a FPGA processing engine with mezzanine-based ADCs using form-factors like FMC or XMC.
For this month’s Jeff’s Picks section COTS Journal evaluated several ADC and DAC conversion products based on three aspects: technology leadership, design innovation and market relevance. The winning product is the PVP-7xx family of A-D processing boards from Star Communications (Figure 1). This family is scalable from 1 to 4 A/D channels and from 1 to 4 FPGAs (Xilinx high-end Virtex-7 XC7VX485T). According to the company, the product is based on a small, multi-channel A-D component that uses high-speed serial links to route sample data to FPGAs on the board.
Each HSSL link consists of a differential pair operating up to 4 Gbits/s, and protected using SONET scrambling and Hamming error correcting codes. Use of HSSL has several PCB design benefits. First, board area is minimized because each differential pair replaces an entire data bus. Second, routing is simplified because careful length matching of large data busses and their clocks is not needed. Finally, the HSSL is directly compatible with Giga-bit transceivers available on Xilinx Virtex-7 FPGAs. This makes it easy to route all sample data is to every FPGA installed on the board.
Flexible, Programable Design
The PVP features a programmable sample rate, based on a clock generator IC manufactured by Analog Devices. Design benefits include small footprint, flexible referencing options, and a low-phase noise sample clock with programmable frequency. Total board area devoted to clock generation is only 22 x 30 cm. An onboard frequency reference is included having ±2.5 ppm stability over time, frequency, and temperature. Alternatively, customers can supply an external reference anywhere from 1 PPS to 250 MHz in a variety of formats. The board automatically recognizes and switches to the external reference if present. Using the selected reference, the sample clock can be programmed anywhere between 100 MHz to 250 MHz in sub-Hertz steps.
The technology and design innovations result in an A-D product that is small yet very flexible. Flexibility allows the product to support a common architecture that can acquire and process data at the edge of multiple systems. This in turn provides the usual benefits of a common architecture, including scalability, code re-use, common operating procedures, and reduced logistic support. A single board can handle up to four receive channels the intermediate frequency (IF) design allows multiple RF on one board. Front-end bandwidth allows multiple IFs simultaneously—for example 70 and 140 MHz. The board’s programmable sample rate allows users to choose their IF frequency. And the sample rate can be chosen so that it relates to one’s final application which means less filtering is needed. Sample data is synchronized across all receive channels and FPGAs. And because the architecture is scalable, users can scale from one to four FPGAs to scale processing capability to match what’s required.
…And the Runners Up:
8-Channel A/D XMC Provides Radar Phased-Array Solution
Pentek’s Model 71131 is an eight-channel, 250 MHz XMC module featuring 16-bit A/Ds with programmable multiband digital down converters (DDCs) (Figure 2). It’s a member of Pentek’s Jade family of high-performance data converter XMC modules based on the Xilinx Kintex Ultrascale FPGA. The board is suitable for connection to HF or IF ports of a communications or radar system. Its built-in data capture feature offers an ideal turnkey solution as well as a platform for developing and deploying custom FPGA-processing IP. The eight channels make it especially beneficial for multi-channel phased array platforms in defense and weather radar applications where the cost per channel can be substantially reduced.
The front end accepts eight analog HF or IF inputs on front panel MMCX connectors with transformer coupling into four Texas Instruments ADS42LB69 dual 250 MHz, 16-bit A/D converters. The Model 71131 features eight A/D Acquisition IP Modules for easily capturing and moving data. Pentek’s Navigator Design Suite was designed from the ground up to work with Pentek’s Jade architecture and Xilinx’s Vivado Design Suite. The Navigator Design Suite consists of two components: Navigator FDK (FPGA Design Kit) for integrating custom IP into Pentek sourced designs and Navigator BSP (Board Support Package) for creating host applications.
Upper Saddle River, NJ
FMC Offers Four ADCs, Two DACs and High SNR Performance
Innovative Integration’s FMC-SDF is an FMC module that features four 24-bit, ADCs and two, 18-bit DACs, each simultaneously-sampling and DC-accurate (Figure 3). These ultra-high resolution, sigma-delta devices support high dynamic range applications such as stimulus-response, ATE, and seismic data acquisition. Ultra-low jitter clock and trigger controls provide ultimate analog fidelity coupled with precisely framed acquisition and playback. Captures may be triggered via software or external LVCMOS edges.
The FMC-SDF power consumption is under 15 W for typical operation. The module may be conduction cooled using a VITA20 standard heat-spreader. The product may be conformal coated and ruggedized for wide-temperature operation from -40 to +85 degrees C operation and exposure to 0.1 g2/Hz vibration. Support logic in VHDL is provided for Innovative’s broad line of FPGA-accelerated FMC carriers. The Framework Logic package supports development under Xilinx Vivado using VHDL or HLS (high-level synthesis). Additionally, the Matlab BSP within the Framework supports real-time hardware-in-the-loop development using the graphical block-diagram Simulink environment and Xilinx System Generator.
Simi Valley, CA
Check Out These D-A and A-D Conversion Boards Too…
The FMC121 from Abaco Systems (formerly 4DSP) provides two 16-bit A/D channels up to 1Gsps and two 16-bit D/A channels up to 1.4 Gsps data rate with a 2.8 GSPS update rate. The design is based on TI’s ADS54J60 A-D and DAC39J84 D-A converters.
Abaco Systems, Huntsville, AL. (866) 652-2226, www.abaco.com
Acromag’s AP220 module from its AcroPack series is a 12-bit DAC Module with 16 channels voltage outputs and wide temperature range. When used with a carrier that holds two AcroPack AP modules, up to 32 voltage outputs can be obtained from a single card cage slot.
Acromag, Wixom, MI. (248) 295-0310 www.acromag.com
The XRM2-ADC-D9 from Alpha Data is an I/O Module which provides two Analog to Digital convertors with 14-bit resolution at sampling rates up to 500MHz. The XRM is aimed at IF/Baseband Signal Sampling applications.
Alpha Data, Denver, CO. (303) 954-8768. www.alpha-data.com
The WWQA05 from Annapolis Micro Systems is a Quad 500 Msamples/s 16-Bit ADC WFMC+. It has four input bandwidth options, internal sample clock options and internal 10MHz reference clock options. The board is compatible with any WILDSTAR mainboard with a WFMC+ slot.
Annapolis Micro Systems, Annapolis, MD. (410) 841-2514. www.annapmicro.com
The CHAMP-WB-A25G is a board set from Curtiss-Wright that couples the dense processing resources of a single large Xilinx Virtex-7 FPGA with a high-bandwidth 25 Gsample/s 8-bit ADC module in a commercial grade 6U OpenVPX (VITA 65) form factor module.
Curtiss-Wright Defense Solutions, Ashburn, VA. (703) 779-7800. www.cwcdefense.com
The Echotek Series DCM-V6-XMC Module from Mercury Systems combines the latest wideband high-performance ADC with a high-speed, high-resolution DAC, both working in conjunction with Xilinx Virtex-6 technology. The 12-bit ADC samples at up to 3.6 GSPS.
Mercury Systems, Chelmsford, MA. (978) 967-1401. www.mrcy.com
Vadatech’s VPX599 provides dual-channel ADC with sample rates of up to 6.4 GSPS at 12-bits and a dual DAC update rate of up to 12 GSPS and direct RF synthesis at 6 GSPS at 16-bits making it suitable for signal capture/analysis applications such as COMINT, SIGINT and radar.
Vadatech, Henderson, NV. (702) 896-3337. www.vadatech.com