The Phase Lock Loop Technique - Agilent Technologies E5500A User Manual

6 Absolute Measurement Fundamentals

The Phase Lock Loop Technique

The Phase Lock Loop Technique
Understanding the
Phase-Lock Loop
Technique
Figure 6-1 Simplified Block Diagram of the Phase Lock Loop Configuration
The Phase Lock Loop
Circuit
6-2 E5500 Phase Noise Measurement System Version A.02.00
The phase lock loop measurement technique requires two signal
sources; the source-under-test and a reference source. This
measurement type requires that one of the two sources is a
voltage-controlled-oscillator (VCO).
You will most likely use the phase lock loop technique since it is the
measurement type most commonly used for measuring signal source
devices. This chapter focuses on this measurement type for signal
source measurements.
This measurement technique requires two signal sources set up in a
phase locked loop (PLL) configuration. One of the sources is the
unit-under-test (UUT). The second source serves as the reference
against which the UUT is measured. (One of the two sources must be
a VCO source capable of being frequency tuned by the System.)
Figure 6-1 shows a simplified diagram of the PLL configuration used
for the measurement.
The Capture and Drift Tracking Ranges
Like other PLL circuits, the phase lock loop created for the
measurement has a Capture Range and a drift tracking range. The
Capture Range is equal to 5% of the system's peak tuning range, and
the drift tracking range is equal to 24% of the system's peak tuning
range.
Document Part No. E5500-90024 Ed. 1.0