Response Types - Agilent Technologies N4413A User Manual

Performing Time Domain Measurements

Response Types

Response Types
Agilent multiport test systems are able to display the response of a device as if it were
stimulated with either a step or an impulse waveform. The algorithm that is used is robust
enough that it can determine either type of response, even for band-limited devices.
Furthermore, it is not necessary for the device to be able to operate at DC. Both Time Domain
Transmission (TDT) and Time Domain Reflection (TDR) parameters can be displayed on the
horizontal axis either as a time or a distance. It is also possible to enter a velocity factor so
that the electrical length corresponds with the physical length of the DUT.
The time scale of transmission parameters shows the propagation delay through the device.
The time scale of the reflection parameters shows the characteristics of the DUT at a certain
time delay into the device. Therefore, the reflection parameter shows the one-way travel time
into the device, not the round-trip propagation delay that other instruments may show.
On the vertical axis, the impulse response is a reflection or transmission coefficient displayed
on either a linear or a logarithmic scale. This parameter can be displayed as an absolute
number, or relative to a minimum or maximum value of the response.
Likewise, the step response can be displayed on either a linear or a logarithmic scale.
Alternatively, a reflection parameter can be displayed as impedance versus time rather than
as a reflection coefficient. Any of the single-ended or mixed-mode S-parameters can be
displayed in the time-domain. The table below shows the relationship between frequency
domain parameters to their time domain equivalents.
Relationship of Frequency Domain Parameters to Time Domain Equivalents
Mode
UNBALANCED
UNBALANCED
UNBALANCED
UNBALANCED
UNBALANCED
UNBALANCED
UNBALANCED
UNBALANCED
82
Direction Type
N/A TDR
REVERSE TDT
REVERSE TDT
REVERSE TDT
FORWARD TDT
N/A TDR
REVERSE TDT
REVERSE TDT
Parameter
S11
S12
S13
S14
S21
S22
S23
S24
Chapter 4