News and New Products

Small, 1-GHz-bandwidth, two-channel PCI digitizer offers low power consumption

By Dan Strassberg, Contributing Technical Editor -- EDN, 6/27/2007

Look twice at the photo of Agilent’s new Acqiris DP1400 low-power, two-channel digitizer, which provides guaranteed 1-GHz minimum –3-dB bandwidth on each channel and can capture 2G 8-bit samples/sec in the single-channel mode. You may notice that the panel bears both the Acqiris and Agilent names because Acqiris has been part of Agilent since 2006. Then, note that the DP1400 is not a CompactPCI board; the short format can fool you. The board plugs into the standard 66-MHz, 32-bit PCI bus, so it works in standard desktop PCs. Most other boards in this class are full-length, even though dense PC packaging is now making full-length slots increasingly rare. Those large boards also tend to be power-hungry; some use nearly 60W, and several draw 30W. The DP1400 uses less than 15W.

The DP1400 offers an unusual optional multibuffer-simultaneous-acquisition-and-readout) mode, which lets you divide the board’s internal 256-kbyte (128-kbyte/channel) memory into as few as three or as many as 960 segments, make conversions with a maximum dead time of 350 nsec, and rapidly send the data to the host PC while acquisition continues. Although the mode does not prevent the board from acquiring data faster than the PCI bus can remove it from the buffers, should all of the buffers momentarily become full, onboard logic temporarily suspends conversions whose results would otherwise overwrite previously acquired data.

For those interested in implementing random repetitive sampling, a mode normally associated with digital oscilloscopes but not with data-acquisition boards, the DP1400 contains a TDC (time-to-digital converter), part of the hardware you need to sample repetitive waveforms at an equivalent rate of 40G samples/sec.

The unit offers seven full-scale input ranges from 50 mV to 5V in a 1-2-5 sequence with offsets adjustable to ±2V on ranges to 500 mV and ±5V on less sensitive ranges. Each ADC samples at rates from 100 to 1G samples/sec in a 1-2-5 sequence, and you can interleave the two converters to double these rates. Besides the full-bandwidth mode, the board provides internal 20-, 200-, and 700-MHz lowpass filters for its analog inputs. Timebase error is less than ±2 ppm, and trigger jitter is less than 2 psec rms on a 10-μsec record. The unit offers a variety of trigger modes and can pretrigger to as much as the full record duration. The board also incorporates a second-generation autosynchronous-bus system that can distribute trigger and clock signals to multiple modules. Prices starts at $9490; the simultaneous-acquisition-and-readout option adds $1000.