Digitiser is based on PXIe instrumentation
High-speed digitisers from Spectrum are based on the PXIe (PXI Express) modular instrumentation standard. The M4x.44xx series consists of six products, each packaged in a dual-width 3U module and incorporating a four-lane PCI Express Generation 2 interface. The high-performance interface allows data transfer speeds in excess of 1.7Gbyte/s, for use in today’s fastest PXIe mainframe systems, says the company.
The digitisers include versions with two and four synchronous channels and with resolutions of either 14bits, for sampling at rates up to 500Msample/s, or 16bits, for sampling at rates up to 130 or 250Msample/s. With analogue bandwidth up to 250MHz, the digitisers are suited to use in ATE systems to acquire and measure electronic signals in the 1.0 to 200MHz range. Typical applications are found in semiconductor and component testing, radar, wireless communications, medical science, automotive, power, physics, surveillance, aerospace and defence.
The cards feature an oscilloscope-style front-end. Each channel has its own separate monolithic ADC and low noise signal conditioning circuitry. Fully programmable, the cards provide six gain input ranges (±200mV up to ±10V), selectable input impedance of 50Ohms or 1MOhms and AC or DC coupling. An internal bandwidth filter can be activated where high frequency noise that may mask signals needs to be suppressed.
The trigger source can be any of the input channels, either of the two external trigger inputs, any of the eight PXI trigger lines or the PXI star trigger. Trigger modes include positive or negative edge, both edges (window), software and rearm. Logic triggering can be implemented based on the state of the channel and the external trigger inputs.
The clocking system of the digitisers is precise and advanced. The clock can be internally or externally generated (including as source the 100MHz PXIe differential clock and the 10MHz PXI clock). It has a built-in 10MHz reference and, if required, it can be synchronised with other reference sources. A fine-resolution mode is also available that allows clock rates to be selected with 1Hz resolution. The feature makes it possible to program the sampling rate of the digitisers to match that of other devices or to setup acquisitions for specialised input signal conditions.
All the digitisers come with a standard 4Gbyte (2Gsamples) of on-board acquisition memory to acquire long and complex signals. Single-shot capture (transient recording), streaming (FIFO), segmented (Multiple Recording), gated (Gated Sampling), or the combination of segmented acquisition of fast signals is offered in parallel with slow continuous data recording (ABA mode). All trigger events can be time-stamped.
The digitisers have high dynamic performance, says the company. For example, signal-to-noise ratios (SNR) are typically over 70dB, spurious free dynamic range (SFDR) is better than 90dB, and total harmonic distortion (THD) is less than -70dB. The combination is claimed to not only make it possible to detect small signals on large ones but it also produces better measurement repeatability, precision and accuracy.
To control and operate the digitizers, the company provides its SBench 6 program. It supports all the key functions of the digitiser as well as providing data display, storage, analysis and documentation. It offers both oscilloscope and transient recording modes, including data streaming.