News and New Products

Onboard FPGAs enable high-performance ADC modules to analyze data at unprecedented speeds

By Dan Strassberg, Contributing Technical Editor -- EDN, 9/22/2009

Agilent’s Acqiris product group recently announced three high-speed, high-accuracy, wide-dynamic-range, modular digitizers. The new products, which build on the manufacturer’s expertise with the VME (Versa Module Eurocard) and VXS (VME-switched/serial) modular formats, perform high-speed signal processing of the acquired data using onboard user-programmable FPGAs. Although much of Acqiris’ work focuses on meeting the data-acquisition needs of defense-and-aerospace-system manufacturers, the new products will also find application in such areas as medical imaging, scientific instrumentation, nondestructive testing, storage testing, LIDAR (light detection and ranging), validation of mixed-signal semiconductors in automated-test equipment, and advanced research in high-energy physics, nuclear physics, and astrophysics.

The four-channel, 12-bit SVM3500 digitizer allows channel interleaving that enables acquisition at rates to 2G samples/sec. The module focuses on applications in radar, EW (electronic warfare) and SI (synthesized instrumentation). The input-amplifier bandwidth is more than twice the minimum for accurate reproduction of signals that you can digitize without aliasing at 2G samples/sec.

The unit adds an analog-digitizer mezzanine board, which includes four 12-bit, 500M-sample/sec ADCs, to the manufacturer’s U1083A VME/VXS base module. Also on the mezzanine board is the MCK clock-distribution circuit, which distributes throughout the board very-low-added-jitter in-phase, quadrature, or out-of-phase versions of an external clock. These clock signals allow interleaved acquisition at rates to 2G samples/sec. In the interleaved mode, an FIR (finite-impulse-response) filter, implemented in an on-mezzanine Xilinx Virtex-5 FPGA, corrects for static offset and gain errors and frequency-dependant gain and delay mismatch among the ADCs. This FPGA also includes an externally accessible look-up table, The resulting analog performance, which includes SFDR (spurious-free dynamic range) to 80 dBc at 500M samples/sec and 70 dBc at 2G samples/sec, THD (total harmonic distortion) of −80 dBc at 500M samples/sec and −79 dBc at 2G samples/sec, and SNR (signal-to-noise ratio) greater than 62 dBc, maintains more than 10 effective bits over a 10-MHz to 1-GHz band.

The base card provides high-performance, real-time data processing by means of the large SX55 and FX100 Xilinx Virtex-4 FPGAs. The board supports eight 3.125-Gbps serial links on the VXS backplane. Two optical links on the front panel support data transfers at rates to 3.125 Gbps, making the aggregate data bandwidth more than 3.5G bytes/sec. The fully compliant VME64x interface supports the 2eSST (two-edge-source-synchronous-transfers) protocol. The optional FDK (firmware-development kit) helps you develop applications for the SX55 and FX100 FPGAs. The FDK includes a set of cores that easily interface to the underlying hardware, a base design for each family member to provide simple, ready-to-use designs, and a test-bench environment for design and simulation.

The signal-peak-detection firmware-processing option is an important enhancement in the dual-channel, 8-bit, four-lane, U1084A PCIe (Peripheral Component Interconnect Express) high-speed digitizer, which acquires as many as 4G samples/sec. This digitizer with onboard FPGA offers 1.5-GHz bandwidth and incorporates a 15-psec TTI (trigger-time interpolator) for accurate timing measurement. The FPGA-based peak-detection and -analysis firmware provides real-time signal processing depending on the processing firmware you choose and allows real-time acquisition and peak detection at data rates to 4G samples/sec.

Firmware options allow the data-converter card to perform user-defined postprocessing tasks, which you can easily upload into the FPGA under program control. These tasks can redefine the way in which the card acquires and processes data, making the system flexible and easy to reconfigure. The signal-peak-detection firmware option enables the board to create a peak histogram of successive acquisitions, with each histogram bin containing peak counts or summed peak amplitudes. The unit can record as many as 60M peaks/sec and exhibits trigger jitter of just 250 psec. With the high-speed PCIe bus, the onboard processing maximizes data and measurement throughput. The digitizer outputs data at rates to 650 Mbytes/sec. Software drivers for Windows and Linux enable you to easily integrate the U1084A into measurement systems or use it to replace or upgrade other high-speed Acqiris data converters.

The eight-channel, 14-bit SVM4800 digitizer’s input-signal bandwidth exceeds 300 MHz. The unit achieves acquisition as fast as 125M samples/sec. Like the 12-bit SVM3500, the SVM4800 adds an analog-digitizer mezzanine card to the U1083A VME/VXS base card. In the SVM4800, this digitizer includes two dc-coupled, 14-bit, 125M-sample/sec, four-channel ADCs. SFDR is 82 dBc, THD is −82 dBc, and SNR is greater than 70 dBc, leading to an effective resolution of more than 11.2 bits at 125M samples/sec. The mezzanine card also includes a Xilinx Virtex-5 FPGA that provides data multiplexing and static data-gain and offset correction. Other features of this module are similar to those of the SVM3500. Intended applications include ES (electronic-support) and ECM (electronic-countermeasures) systems.

Prices depend on product configuration/application and quantity, but US single-unit prices for full-featured products begin at $26,500 for the U1084A, $46,000 for the SVM3500 (U1083A-005), and $42,000 for the SVM4800 (U1083A-007).