Mechanical influences on a cable (vibration, sound waves, friction, bending etc.) can induce electrical charges by triboelectric effects leading to significant extra noise typically in the low frequency range from quasi-DC up to 100 kHz. When measuring very low currents in the nano-, pico- and femtoampere region this microphonic noise may become the dominating noise source.
Even when located in a relatively quiet and silent environment any micro-movement of the cable can produce significant noise levels making a real low noise signal measurement impossible.
FEMTO´s low noise cables are manufactured with a special semi-conductive layer between the dielectric and shield to counteract effectively the microphonic noise. The careful test and evaluation process we have performed in our femtoampere-laboratory showed our CAB-LN1 cable being the best-in-class cable also in comparison to many low noise cables available in the market. Due to the superior cable design the noise reduction compared to ordinary e.g. RG58 or RG174 cable is typically more than 1,000 times.
Performing low current or low charge measurements requires signal cables with very high insulation resistance in order to avoid additional thermal resistance noise. A high insulation resistance is also important for preventing the low currents/charges from flowing to ground (shield) and therefore not contributing to the signal measurement. The cable used in the CAB-LN1 series is a very high insulation type. In addition all FEMTO low noise cables are equipped with ultra-high insulation connectors preserving the high insulation resistance also for the completely assembled cable. Before shipping each cable is thoroughly tested to meet the insulation resistance specification of > 1014 Ω.
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The photoreceiver series HSA-X-S was broadened by two models featuring an improvement in noise performance of up to 40%. The output reflection coefficient was reduced by 8 dB at the same time.
FEMTO® Messtechnik GmbH
Phone: +49-(0)30-280 4711-0
Fax: +49-(0)30-280 4711-11
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