Cisco Cisco 1 GHz GainMaker Amplifier 설치 가이드
741338 Rev D
Introducing Trim Networks
1-3
Trim Facts
Trim Network Response Characteristics
Trim network response characteristics must be fully understood prior to
commencing the sweep process. When selecting a trim, choose one that produces
only the desired effect at one frequency. While tuning the trim network, observe the
portions of bandwidth that appear flat. Ensure that no anomalies (peaks or dips) are
introduced into unneeded areas.
Most trims have two controls. One control is a variable capacitor for frequency
Most trims have two controls. One control is a variable capacitor for frequency
control and the other is a variable resistor for amplitude control.
Insertion Loss
Insertion loss must be considered when selecting a trim network. Insertion loss is an
important consideration during the system design process, as the typical trim
network reduces the amplifier gain by an average of 2 dB. If the amplifier is
designed with minimum input, installing a trim network may not allow the
amplifier to reach the proper RF output level.
Frequency Control
The variable capacitor (C1 in the frequency response plots) varies the frequency of
the dip or peak. Depending on the design parameters of the trim network, the
variable capacitor usually varies frequency 10 MHz to 100 MHz from nominal.
Amplitude Control
The variable resistor (R1 in the frequency response plots) varies the amplitude of the
dip or peak and insertion loss. The typical variable resistor varies peak or dip
amplitude between 1 dB and 3 dB.
Introducing a deeper dip increases the overall insertion loss. Likewise, introducing a
Introducing a deeper dip increases the overall insertion loss. Likewise, introducing a
higher peak increases the insertion loss.
Bench sweeping each trim allows the technician to gain a full understanding of the
Bench sweeping each trim allows the technician to gain a full understanding of the
trim’s operation. This can lead to reduced system downtime and increased
productivity.