High-speed 14 and 16 bit PXIe digitizers

June 14, 2016 // By Graham Prophet
Spectrum (Grosshansdorf, Germany) has added a high-speed digitizer product line 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 1.7 GB/sec, suiting the cards ideal for use in today’s fastest PXIe mainframe systems. The digitizers include versions with two and four fully synchronous channels and they come with resolutions of either 14 bits, for sampling at rates up to 500 Msample/sec, or 16 bits, for sampling at rates up to 130 or 250 Msample/sec. With analogue bandwidth up to 250 MHz, the digitizers are suited to use in ATE systems where electronic signals in the 1 to 200 MHz range need to be acquired and measured with the best possible speed and precision.

The M4x.44xx series 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 (±200 mV up to ±10 V), selectable input impedance of 50 Ω or 1 MΩ and AC or DC coupling. An internal bandwidth filter can be activated in situations where high frequency noise, that may mask signals, needs to be suppressed.

The flexible front-end circuitry is complemented by a powerful trigger system and versatile clock. 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 clock can be internally or externally generated (including as source the 100 MHz PXIe differential clock and the 10 MHz PXI clock). It has a built-in 10 MHz reference and, if required, it can be synchronized with other reference sources. A fine-resolution mode is also available that allows clock rates to be selected with 1 Hz resolution. The feature makes it possible to program the sampling rate of the digitizers to match that of other devices or to setup acquisitions for specialized input signal conditions. All the digitizers come with a standard 4 GByte (2 Giga-Samples) of on-board acquisition memory.