Atek HP 8753D, User Manual, Page: 425 / 677

Amplitude and Phase Tracking
The match between mixers is dened as the absolute dierence in amplitude and/or phase
response over a specied frequency range . The tracking between mixers is essentially how well
the devices are matched over a specied interval. This interval may be a frequency interval or
a temperature interval, or a combination of both.
Y ou can make tracking measurements by ratioing the responses of two mixer conversion loss
measurements . Then any dierence you view in response is due to the mixers and not the
measurement system.
Replace mixer A with the mixer that you want to compare it to . Mixer R should always remain
in place as the reference mixer .
Figure 6-97.
Connections for an Amplitude and Phase Tracking Measurement Between Two Mixers
Phase Linearity and Group Delay
Group delay is the rate of change of phase through a device with respect to frequency (d /d! ).
Traditionally , group delay has been used to describe the propagation delay ( g), and deviation
from linear phase through a linear device . However , this parameter also contains valuable
information about transmission delay and distortion through a non-linear device such as a
mixer or frequency converter . F or example , at group delay corresponds to low modulation
distortion (that is , carrier and sidebands propagate at the same rate).
Phase linearity and group delay are both measurements of the distortion of a transmitted
signal. Both measure the non-linearity of a device's phase response with respect to frequency .
Application and Operation Concepts 6-159