Spectrum pre-amplifiers

For applications where low-level electronic signals need to be analysed, Spectrum pre-amplifiers can be used to boost signal levels. Seven different versions are available, offering gain ranges from 20 to 60 dB, bandwidths from 10 MHz to 2 GHz, and 50 Ω and 1 MΩ terminations. Most of the pre-amplifiers have true DC coupling and an adjustable output offset control to extend their operational use.

The 16-bit M2i.46xx series digitisers come with eight programmable input settings offering from 50 mV to 10 V full-scale range (FSR). Using an SPA.1231 pre-amplifier can provide an additional gain of either 40 or 60 dB, effectively delivering an FSR that can go as low as 50 μV. The low FSR, together with the 16-bit resolution of the digitiser, makes it possible to detect signal variations in the nanovolt range.

The pre-amplifier SPA.1841, with a bandwidth of 2 GHz, matches the Spectrum M4i.22xx series digitisers with a 5 GS/s sampling rate and a bandwidth up to 1.5 GHz. Using the combination of a M4i.2230-x8 and a SPA.1841 amplifier, one can sample signals in the GHz range with an FSR of 2 mV resulting in a resolution of 15 μV per step at the given digitiser resolution of 8 bit.

SPA series pre-amplifiers are optimised for minimum input noise with models available that reach values as low as 0.9 nV/√Hz. For applications that need to push the technology further, signal processing functions, such as averaging and filtering, can be used on the digitised data.