Application of second-tier VNA calibration

　　ith C d Mi t h Wi C l XE™

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　　resulting error set for the VNA error

　　correction.

　　Two Tier Calibration of a Vector Network Analyzer is a technique that allows two calibration error sets to be combined into one

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　　ƒTwo Tier Calibration of a Vector Network

　　What is Two Tier Calibration?

　　calibration error set alone.

　　ƒThis technique solves VNA calibration problems that are not easily solved by one

　　lib ti t l

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　　coaxial port on one side and a probed port on the other side.

　　ƒAnother example would be a device with a different probe pitch on each port.

　　ƒThe dilemma is finding a“Thru”calibration standard to use for the

　　y p

　　you will run into a dilemma to complete the calibration with one set of calibration standards.

　　ƒThe most common example of a DUT with mixed ports is one with a i l t id d b d t th th id

　　The dilemma is finding a Thru”calibration standard to use for the

　　calibration of the VNA between such ports.Short,Open,and Load standards for the VNA calibration of the two ports are rather simple.The“Thru”is the issue.

　　ƒWhen you have a device under test that has mixed port connections

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　　me to solve?

　　What sort of problem will Two Tier Calibration help me to solve?

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　　Thru,assuming a suitable thru exists at all.This is like the Chicken and the Egg;Which came first?

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　　q)

　　ƒEffectively the Two Tier Calibration yields the S-Parameters of the Thru,thus solving the dilemma.

　　ƒAnd you’ll see that Two Tier Calibration is a simpler procedure.

　　ƒFor the example of a DUT with a coaxial port and a probed port,you could complete a 2-port VNA calibration if you had the S-Parameters of a second probe to use as the calibration Thru.

　　ƒYou face the same dilemma,how to measure the S-Parameters of the

　　complete the calibration?

　　Can’t I just use S-Parameters of the Thru to

　　complete the calibration?

　　Even though Cascade Microtech provides S-Parameters for probes we

　　manufacture,your best VNA calibration should include your cable to probe connection,and your VNA sweep setup(number of points,frequencies,IF bandwidth,etc).

　　ƒEven though Cascade Microtech provides S Parameters for probes we

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　　VNA with the additional probe calibration.

　　–The result is you have the VNA calibrated now to your two desired reference planes,coax on one side and probe tip on the other side.

　　which will combine the existing two port calibration already in the

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　　reference planes,coax on one side and probe tip on the other side.

　　Two Tier Calibration Procedure

　　a probed port on the other side,here is the procedure:

　　–From the front panel of the VNA,complete a full two port coaxial calibration to the ends of the two VNA test port cables using coaxial calibration standards or an electronic calibration module.

　　ƒFor the common example of a DUT with a coaxial port on one side and a probed port on the other side here is the procedure:

　　–Connect one VNA test port cable to the probe you are using to contact the probed side of your DUT.

　　–Within the WinCal XE calibration menu select“Second Tier”.

　　–And then complete a 1-Port calibration to the tip of the probe using Short,Open,and Load calibration standards.

　　–Finish by sending the probe calibration error terms to the VNA,which will combine the existing two port calibration already in the

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　　p og ess e y t oug t e data e e d esu t s a S parameters of the probe are determined.It works great!”

　　S12 S21.The last product is pulled apart by square root with a

　　ƒEngineering:“Measurement of three standards,Short,Open,and Load at the tip of the probe provides three(complex)equations with three unknowns(complex):S11,S22,and

　　S12*S21 The last product is pulled apart by square root with a

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　　It works great!

　　Engineering:“Measurement of three standards Short Open

　　ƒMarketing:“It works great!”

　　through the data.The end result is all 4 S-

　　How does it work?

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　　WinCal XE as shown below.

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　　•After finishing the two port coaxial calibration of the VNA from the instrument front panel,proceed with

　　WinCal XE as shown below

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　　Step by Step for This Example

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　　complete you are done with the calibration!See how simple it is.

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　　•Finish by sending the probe calibration error terms to the VNA,which will combine the existing two port calibration already in the VNA with the additional probe calibration.After this step is complete you are done with the calibration!See how simple it is

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　　Step by Step for This Example

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　　WinCal XE

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