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www.us-tech.com
August, 2017
Spectrum Ups the Sensitivity of Modular Digitizers
By Oliver Rovini, Technical Director, Spectrum Instrumentation
speed 22xx series of digitizer prod- ucts that increases their sensitivity and absolute resolution for low amplitude signals in the ±40 mV up to ±0.5V range. The current products are optimized to acquire, store and analyze signals in the ±200 mV up to ±2.5V range. The M4i.22xx-ir40m provides sampling rates up to 5 GS/s with 8-bit analog-to-digital converter (ADC) resolution and high SNR. The devices are available in PCIe, PXIe and LXI form factors. The modular way that Spec -
S
trum designs and build its products, allows it to provide this front-end option very easily as a new daughter board within the 22xx range. Matching the digitizer's range to the signal under test is important as it ensures maximum dynamic range, as well as better measurement accuracy and resolution. For example, if a sig- nal only covers half of a digitizer's selected full scale range, then only half of the digitizer's available ADC resolution can used. Smaller, or lower-level signals
will use even less of the ADC’s capa- bilities and further reduce the digi- tizer’s overall signal-to-noise per- formance.
Spectrum 22xx series digitizers.
pectrum Instrumentation has added an option, M4i.22xx- ir40m, to its successful, high-
Increasing Sensitivity This new option lets users select
more sensitive, full scale ranges so that, even for low amplitude signals, the ADC’s complete dynamic range is available. The company now offers solutions for such applications as a
10-bit digitizer with a lowest 50W range at ±0.5V full-scale input that has to acquire a signal with an amplitude of around 50 mV. The 10-bit ADC offers 1,024
(210) levels of resolution each of about 1 mV (1V/1,024). The signal would therefore only cover about 50 levels
of the 10-bit ADC’s available range. Spectrum’s 22xx series digitiz-
ers use 8-bit ADCs that give 256 (28) levels of resolution. So, by using this new low-range option, the digitizer becomes more sensitive with around 0.3 mV (80mV/256) of resolution cap- turing the 50 mV signal with around three times more resolution than the more expensive 10-bit unit. For extremely low amplitude
signals, the 22xx series digitizers can also be used with Spectrum’s high bandwidth (up to 2 GHz) external SPA series amplifiers. These free- standing units offer additional times 10 (20 dB) or times 100 (40 dB) gain, making it possible to capture and analyze signals that go down into the low millivolt ranges. The company’s 22xx series digi-
tizers come in a variety of popular form factors including PCIe, PXIe and LXI. Models are available with sampling rates of 1.25, 2.5 and 5 GS/s and bandwidths of 500 MHz or 1.5 GHz (700 MHz with low input range option). Versions with one, two and four channels are available for units in the PCIe and PXIe formats, while the larger LXI-based instru- ments offer models that have from 2 to 24 fully-synchronous channels. The digitizers are designed so
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Manufactured in the U.S.A. since 1966
www.westbond.com
1551 S. Harris Court Anaheim, CA 92806 Tel 714·978·1551
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