Integrated vector network analyzer
A method is provided for determining source match of a test system including an RF source, a vector network analyzer (VNA) and a test port. The method includes connecting a first calibration standard to the test port; generating an RF signal using the RF source, and applying the RF signal to the first calibration standard; measuring a first incident signal of the RF signal at a first receiver of the test system, and measuring a first reflected signal at a second receiver of the test system; connecting a second calibration standard to the test port; measuring a second incident signal of the RF signal at the first receiver of the test system, and measuring a second reflected signal at the second receiver of the test system; and determining the source match of the test system using the first incident and reflected signals and the second incident and reflected signals.
1. A method of determining a source match of a test system, comprising a radio frequency (RF) source, a vector network analyzer (VNA) and a test port, the method comprising:
connecting a first calibration standard to the test port;
generating an RF signal using the RF source, and applying the RF signal to the first calibration standard;
measuring a first incident signal of the RF signal at a first receiver of the test system, and measuring a first reflected signal at a second receiver of the test system;
connecting a second calibration standard to the test port;
measuring a second incident signal of the RF signal at the first receiver of the test system, and measuring a second reflected signal at the second receiver of the test system; and
determining the source match of the test system using the first incident signal, the first reflected signal, the second incident signal and the second reflected signal, wherein is determining the source match comprises determining a ratio of (i) a difference between the first incident signal and the second incident signal and (ii) a difference between the first reflected signal and the second reflected signal.
2. The method of claim 1 , wherein the first calibration standard is a short and the second calibration standard is an open.
3. The method of claim 2 , wherein the source match (Sm) is determined as:
Sm =( a 1_Short− a 1_Open)/( b 1_Short− b 1_Open),
wherein a1_Short is the first incident signal, a1_Open is the second incident signal, b1_Short is the first reflected signal, and b1_Open is the second reflected signal.
4. The method of claim 1 , further comprising:
initially connecting calibration standards to the test port; and
generating another RF signal at the RF source as another incident signal applied to the calibration standards, and determining S-parameter correction terms to provide S-parameter calibration at the test port using the another incident signal and another reflected signal based on the another incident signal,
wherein determining the source match further uses the S-parameter correction terms.
5. The method of claim 1 , wherein the source match varies versus frequency and power level of the RF signal generated using the RF source.
6. A test instrument, including an embedded vector network analyzer (VNA) circuit, for testing a device under test (DUT), the test instrument comprising:
a radio frequency (RF) source configured to generate an RF signal during a calibrating stage;
a test port configured to connect to each of a first calibration standard and a second calibration standard for determining a source match of the RF source;
a first receiver configured to measure a first incident signal of the RF signal through a first coupling device with the test port connected to the first calibration standard, and to measure a second incident signal of the RF signal through the first coupling device with the test port connected to the second calibration standard;
a second receiver configured to measure a first reflected signal responsive to the first incident signal of the RF signal through a second coupling device with the test port connected to the first calibration standard, and to measure a second reflected signal responsive to the second incident signal of the RF signal through the second coupling device with the test port connected to the second calibration standard; and
a processing unit programmed to determine the source match of the RF source based on the first incident signal and first reflected signal, and the second incident signal and the second reflected signal, wherein the processing unit is programmed to determine the source match by determining a ratio of (i) a difference between the first incident signal and the second incident signal and (ii) a difference between the first reflected signal and the second reflected signal.
7. The test instrument of claim 6 , wherein the first calibration standard is a short and the second calibration standard is an open.
8. The test instrument of claim 7 , wherein the processing unit is programmed to determine the source match (Sm) of the RF source as:
Sm =( a 1_Short− a 1_Open)/( b 1_Short− b 1_Open),
wherein a1_Short is the first incident signal, a1_Open is the second incident signal, b1_Short is the first reflected signal, and b1_Open is the second reflected signal.
9. The test instrument of claim 6 , wherein:
the test port is further configured to initially connect to each of a plurality of different calibration standards,
the RF source is further configured to initially generate a calibration RF signal as a calibration incident signal applied to each of the plurality of different calibration standards, and
the processing unit is further configured to determine S-parameter correction terms for providing S-parameter calibration at the test port based on the calibration incident signal and a calibration reflected signal responsive to the calibration incident signal, and to determine the source match further based on the S-parameter correction terms.
10. The test instrument of claim 6 , wherein the source match varies versus frequency and power level of the RF signal generated by the RF source.
11. The test instrument of claim 6 , wherein the test instrument is an RF signal generator comprising the RF source, and wherein the embedded VNA circuit comprises the first and second receivers, and the first and second coupling devices, and excludes the RF source.
12. The test instrument of claim 6 , wherein the test instrument is a spectrum analyzer, and wherein the embedded VNA circuit comprises the first and second receivers, the first and second coupling devices, the RF source, and a third coupler for coupling the incident RF signal from the RF source.
13. The test instrument of claim 6 , wherein the test instrument is an oscilloscope comprising the first and second receivers, and wherein the embedded VNA circuit comprises the first and second coupling devices, the RF source, and a third coupling device for coupling the incident RF signal from the RF source, and excludes the first and second receivers.
14. The test instrument of claim 6 , wherein each of the first and second coupling devices comprises one of a coupler, a coupled line structure, a combiner, a diplexer, a splitter, a balun, a bridge, or a resistive divider.
15. A vector network analyzer (VNA) module connectable to different types of test instruments, the VNA module comprising:
a radio frequency (RF) source configured to generate an RF signal during a calibrating stage;
an RF port configured to connect to a test instrument;
a test port configured to connect to each of a first calibration standard and a second calibration standard for determining a source match of the RF source;
a first receiver configured to measure a first incident signal of the RF signal through a first coupling device with the test port connected to the first calibration standard, and to measure a second incident signal of the RF signal through the first coupling device with the test port connected to the second calibration standard;
a second receiver configured to measure a first reflected signal responsive to the first incident signal of the RF signal through a second coupling device with the test port connected to the first calibration standard, and to measure a second reflected signal responsive to the second incident signal of the RF signal through the second coupling device with the test port connected to the second calibration standard; and
a processing unit programmed to determine the source match of the RF source based on the first incident signal and first reflected signal, and the second incident signal and the second reflected signal, wherein the processing unit is programmed to determine the source match by determining a ratio of (i) a difference between the first incident signal and the second incident signal and (ii) a difference between the first reflected signal and the second reflected signal.
16. The VNA module of claim 15 , wherein:
the test port is further configured to initially connect to each of a plurality of different calibration standards,
the RF source is further configured to initially generate a calibration RF signal as a calibration incident signal applied to each of the plurality of different calibration standards, and
the processing unit is further configured to determine S-parameter correction terms for providing S-parameter calibration at the test port based on the calibration incident signal and a calibration reflected signal responsive to the calibration incident signal, and to determine the source match further based on the S-parameter correction terms.
17. The VNA module of claim 15 , wherein the RF signal is coupled to the first receiver through a third coupling device.
18. The VNA module of claim 15 , wherein the first calibration standard is a short and the second calibration standard is an open.
19. The VNA module of claim 18 , wherein the processing unit is programmed to determine the source match (Sm) of the RF source as:
Sm =( a 1_Short− a 1_Open)/( b 1_Short− b 1_Open),
wherein a1_Short is the first incident signal, a1_Open is the second incident signal, b1_Short is the first reflected signal, and b1_Open is the second reflected signal.
20. The VNA module of claim 15 , wherein each of the first and second coupling devices comprises one of a coupler, a coupled line structure, a combiner, a diplexer, a splitter, a balun, a bridge, or a resistive divider.