Dual -DAC PXI Express Hybrid Peripheral Module
The SMT712 is a PXI Express (opt. Hybrid) Peripheral Module (3U), which integrates two fast 12-bit DACs, 2 banks of 1GByte DDR2 memory each, a clock circuitry and a Virtex5 Xilinx FPGA, under the 3U format.
The PXIe specification integrates PCI Express signalling into the PXI standard for more backplane bandwidth. It also enhances PXI timing and synchronisation features by incorporating a 100MHz differential reference clock and triggers. The SMT712 can also integrate the standard 32-bit PXI signalling as an option.
Both DAC chips are identical and can update their output at up 2.3 Giga-samples per second each, with an 12-bit resolution. The manufacturer is Maxim and the part number is MAX19692. Digital-to-Analog converters are clocked by circuitry based on a PLL coupled with a VCO in order to generate a low-jitter fixed signal. The MAX19692 is capable to achieve SFDR figures close to 70dBs. Each DAC integrates settings depending on the type of frequency response required.
An on-board PLL+VCO chip ensure a stable fixed sampling frequency (maximum rate), in order for the board to be used as frequency synthesizer without the need of external clock signal. The PLL will be able to lock the VCO either on the on-board 100MHz reference or the 100MHz PXI express reference (or 10MHz PXI reference depending on option) or on an external reference signal. The sampling clock for the converters can be either coming from the PLL+VCO chip or from an external source. The reference clock selected is also output on a connector in order to pass it to an other module.
The Virtex5 FPGA is responsible for controlling all interfaces, including PXI (32-bit) and PXIe (8 lanes allocated – depending on PXIe chassis, 4 or 8 lanes would be used), as well as routing samples. The SMT712 is populated with an XC5VLX110T.
Two 1GB DDR2 memory banks are accessible by the FPGA in order to store data on the fly.
An SHB connector is available in order to transfer data/samples from an other Sundance module.
All analog connectors on the front panel are SMA. Examples of application where the SMT712 can be involved in are wideband communication, radar, wireless modem, software radio or waveform generator systems.
Application note SMT702_SMT712 Systems712