S-parameter measurements using real-time oscilloscopes

Patent metadata

Field	Value
Publication number	US-2016018450-A1
Application number	US-201514673747-A
Country	US
Kind code	A1
Filing date	Mar 30, 2015
Priority date	Jul 18, 2014
Publication date	Jan 21, 2016
Grant date	—

Abstract

A method for determining scattering parameters of a device under test using a real-time oscilloscope. The method includes calculating a reflection coefficient of each port of a device under test with N ports, wherein N is greater than one, based on a first voltage measured by the real-time oscilloscope when a signal is generated from a signal generator. The method also includes determining an insertion loss coefficient of each port of the device under test, including calculating the insertion loss coefficient of the port of the device under test to be measured based on a second voltage measured by the real-time oscilloscope when a signal is generated from a signal generator.

First claim

1 . A method for determining scattering parameters of a device under test using a real-time oscilloscope, comprising:
determining a reflection coefficient of each port of a device under test with N ports, wherein N is an integer greater than or equal to one, including:
terminating the ports of the device under test not being measured with a resistor,
and calculating the reflection coefficient of the port of the device under test based on a first voltage measured by the digital oscilloscope when a signal is generated from a signal generator; and
determining an insertion loss coefficient of each port of the device under test, including calculating the insertion loss coefficient of the port of the device under test based on a second voltage measured by the digital oscilloscope when a signal is generated from a signal generator; and providing an absolute time reference between the signal generator and the digital oscilloscope through a synchronized trigger.

2 . The method of claim 1 , further comprising:
sending the signal generated from the signal generator to a first port of a power divider; and measuring the first voltage by the real-time oscilloscope at a second port of the power divider based on the generated signal while the device under test is connected to a third port of the power divider.

3 . The method of claim 2 , wherein N is two, the method further comprising:
sending the signal generated from the signal generator to the port of the device under test not being measured and to the real-time oscilloscope; and measuring the second voltage by the real-time oscilloscope at the port of the device under test being measured based on the generated signal.

4 . The method of claim 2 , wherein N is greater than two, the method further comprising:
sending the signal generated from the signal generator to one port of the device under test not being measured and to the real-time oscilloscope; terminating the remaining ports of the device under test not being measured with a resistor; and measuring the second voltage by the real-time oscilloscope at the port of the device under test being measured based on the generated signal.

5 . The method of claim 1 , wherein the resistor is a 50 Ohm resistor.

6 . The method of claim 2 , wherein the reflection coefficient is calculated using the equations:

b
2

v
s

=

1
2

·

(

1
-

s
22
ss

)



(

s
21

+

s
23



s
~

11
DUT



s
31

)

1
-

s
22
ss



s
12



s
~

11
DUT



s
31

-

s
23



s
~

11
DUT



s
32



s
11
scope

and

s
~

11
DUT

=

s
11
DUT



[

1
-

s
33



s
11
DUT

]

-
1

where b 2 is the first voltage,
ν s is the generated signal,
s 22 ss is an impedance of the signal generator,
s 21 , s 12 , S 31 , S 23 , S 32 , S 33 are the scatter parameter terms of the power divider,
s 11 scope is an input impedance of the real-time oscilloscope, and
s 11 DUT is the reflection coefficient.

7 . The method of claim 3 , wherein N is two and the reflection coefficients are calculated for each port using the equations:

b
2

v
s

=

1
2

·

(

1
-

s
22

Assignees

• Tektronix Inc

Inventors

• Tan Kan
• Pickerd John J

Classifications

• G01R31/2841

  Signal generators · CPC title

• G01R31/2839

  using signal generators, power supplies or circuit analysers (G01R31/2879 takes precedence; multimeters G01R15/12, network analysers G01R27/28) · CPC title

• G01R27/28 Primary

  Measuring attenuation, gain, phase shift or derived characteristics of electric four pole networks, i.e. two-port networks; Measuring transient response (in line transmission systems H04B3/46) · CPC title

• G01R27/16

  Measuring impedance of element or network through which a current is passing from another source, e.g. cable, power line · CPC title

• G01R27/06 Primary

  Measuring reflection coefficients; Measuring standing-wave ratio · CPC title