HP 3048A Operating Manual page 125

Table 3-14. Equipment Requirement for the Phase Lock Loop Measurement (3 of 3)
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Voltage-Controlled-
Oscillator (VCO)
Source
The VCO source can be either the device-under-test or the
reference source. To configure this phase noise measurement,
you will need to know the following information about the VCO
source you are using:
• Tuning Constant (Hz/V) (within a factor of 2)
• Tuning Voltage Range (V)
• Center Voltage of Tuning Range (V)
• Input Resistance of Tuning Port (ohms)
The primary consideration when evaluating a potential VCO
source for your measurement is whether it will provide the
system with sufficient Capture and Drift Tracking Ranges to
maintain lock throughout the measurement. To make this
determination, you must estimate what the drift range of the
sources you are using will be over the measurement period
(thirty minutes maximum). (Details on the relationship between
the Capture and Drift Tracking Ranges and the tuning range of
the VCO source are provided in Chapter 2. This information will
help you evaluate your VCO source based on the estimated drift
of your sources.)
Defining the Measurement
Before you begin entering the measurement parameters into
the HP 3048A, it is a good idea to design your measurement
setup on paper first. Drawing a setup diagram will help you
identify the equipment and accessories you will need. It is
also helpful to list the tuning parameters for the VCO source
you will be using. (Table 3-15 in this example lists the
tuning parameters for several VCO source options.)
The following worksheet shows an example of the design
parameters required for a possible Phase Lock Loop
measurement. (Additional, blank worksheets are provided at
the end of this example for you to use for planning your
measurement.)
Signal Source Applications 3-75