Lake Shore Cryotronics CRX-6.5K, Руководство пользователя

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2.4.3 Basic RF Electrical
Measurements RF measurements can be made with similar configurations described for DC
measurements in section 2.4.2. RF measurements are typically configured with
either a BNC signal connector with ultra-miniature cryogenic coaxial cable or a
K-connector with a semirigid cable as described in section 2.3.2.2. The usable
frequency range of a ZN50 configured with a BNC signal connector with ultra-
miniature cryogenic coaxial cable is DC to 50 MHz. While performance beyond
50 MHz is certainly possible, steps should be taken to understand the losses at the
particular frequency of interest.
The usable frequency range of the ZN50 configured with K-connectors and semirigid
cables provides continuous operation up to 100 MHz and selected band operation up
to 1 GHz. This configuration has reasonable frequency response out to 1 GHz as long
as the band between 200 MHz and 400 MHz can be avoided.
FIGURE 2-22 can add additional information; it shows the forward transmission
response of a pair of ZN50 probes configured with K-connectors and semirigid cable.
While the probes do have a response out to 1 GHz, the separation of the ground path
from the single signal tip of the ZN50 blade causes a large dip in transmission
(forward gain) at 0.3 GHz (300 MHz). Depending on the configuration of the probes
and measurement setup, this dip can vary from approximately 200 MHz to 400 MHz.
2.4.4 Conductive Back
Side Features Special consideration must be given to the choice of a sample holder if the sample is
constructed with conductive features patterned on the back side of the substrate.
Lake Shore offers optional isolated sample holders that have a non-conductive top
surface for this application (FIGURE 2-23). Isolated sample holders also work for
samples constructed on a uniformly conductive substrate. However, coaxial sample
holders should also be considered for this case as described in section 2.4.5.
FIGURE 2-22 Typical forward transmission response of a pair of
ZN50 probes configured with K-connectors and semirigid cable
FIGURE 2-23 Isolated sample holder