Download Simulation - Agilent Technologies

Simulation
Channel Used: Main Channel Frequency and Channel Measurement Bandwidth
Types of Spectrums Used: Same as CNP and CGAIN
Travel Direction: Same as CNP and CGAIN
Traditional Cascaded Noise Figure
NFcascade = F1 + (F2 - 1) / G1 + (F3 - 1) / G1G2 + ... + (Fn - 1) /
G1G2...Gn-1
Note: Traditional cascaded noise figure equations are not used. The are
very restrictive and suffer from the following conditions:
•
Ignore effects of VSWR, frequency, and bandwidth
•
Assume noise contributions are from a single path
•
Ignore mixer image noise
•
Can ignore effects of gain compression
The SPARCA (Spectral Propagation and Root Cause Analysis) technique
used SPECTRASYS does not suffer from these restrictive assumptions.
Occasionally users are troubled if SPECTRASYS simulations give different
answers than the traditional approach. Using SPECTRASYS under the
same assumptions as the traditional approach will always yield identical
answers. To use SPECTRASYS under the same assumptions only
frequency independent blocks like attenuators and amplifiers must be
used. Even so, amplifiers must be used as linear devices with infinite
reverse isolation. Filters cannot be used since their impedance varies with
frequency. Mixers cannot be used since noise from the image band will be
converted into the mixer output. Only 2 port devices must be used because
of the single path assumption. Of course the bandwidth must also be very
narrow.
Channel Noise Power (CNP)
This measurement is the integrated noise power in the main channel along the specified
path.
For example, if the 'Channel Measurement Bandwidth' was specified to 100 kHz and the
'Channel Frequency' was 2000 MHz then the CNP is the integrated noise power from
1999.95 to 2000.05 MHz.
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