Method and apparatus for measuring a device under test using an improved through-reflect-line measurement calibration

A method of measuring a DUT comprising the steps of:

• providing a vector network analyzer having at least two measurement ports,
• measuring a reflection characteristic of a high reflect calibration standard at each measurement port,
• measuring forward and reverse reflection and transmission characteristics of a line calibration standard,
• measuring forward and reverse reflection and transmission characteristics of a source terminated thru calibration standard,
• measuring forward and reverse reflection and transmission characteristics of a locally terminated thru calibration standard,
• calculating error coefficients for said at least two measurement ports based upon results in said steps of measuring,
• calculating a shifted electrical length attributable to said calibration standards based upon results in said steps of measuring,
• connecting the DUT to the measurement ports,
• measuring s-parameters at the measurement ports,
• correcting for systematic errors in said s-parameters based upon said error coefficients to yield a corrected S-parameter matrix, and
• shifting a reference plane for each element of said corrected S-parameter matrix to coincide with a measurement reference plane,
• measuring forward and reverse reflection and transmission characteristics of a source terminated thru calibration standard for indirect pairs of said measurement ports,
• wherein the step of calculating further comprises calculating a different respective shifted electrical length for each said direct and indirect pair, and
• wherein said shifted electrical length between proximal pairs is determined by averaging a shifted electrical length between said direct pair and said indirect pair having respective proximal pair measurement ports in common.

A method of measuring a DUT comprising the steps of:

• providing a vector network analyzer having at least two measurement ports,
• measuring a reflection characteristic of a high reflect calibration standard at each measurement port,
• measuring forward and reverse reflection and transmission characteristics of a line calibration standard,
• measuring forward and reverse reflection and transmission characteristics of a source terminated thru calibration standard,
• measuring forward and reverse reflection and transmission characteristics of a locally terminated thru calibration standard,
• calculating error coefficients for said at least two measurement ports based upon results in said steps of measuring,
• calculating a shifted electrical length attributable to said calibration standards based upon results in said steps of measuring,
• connecting the DUT to the measurement ports, measuring s-parameters at the measurement ports,
• correcting for systematic errors in said s-parameters based upon said error coefficients to yield a corrected S-parameter matrix, and
• shifting a reference plane for each element of said corrected S-parameter matrix to coincide with a measurement reference plane, and
• determining a type of high reflect calibration standard, comprising
• calculating a characteristic of said high reflect calibration standard, fitting arguments of two possible solutions for said characteristics to a straight line, identifying a solution closest to zero phase at DC.

A method of measuring a DUT comprising the steps of:

• providing a vector network analyzer having more than two measurement ports,
• measuring a reflection characteristic of a high reflect calibration standard at each measurement port,
• measuring forward and reverse reflection and transmission characteristics of a line calibration standard for direct pairs of the measurement ports,
• measuring forward and reverse reflection and transmission characteristics of a source terminated thru calibration standard for indirect pairs of the measurement ports,
• measuring forward and reverse reflection and transmission characteristics of a locally terminated thru calibration standard for the indirect pairs,
• calculating error coefficients for said at least two measurement ports based upon results in said steps of measuring,
• calculating a shifted electrical length attributable to said calibration standards based upon results in said steps of measuring for each direct and indirect pair,
• connecting the DUT to the measurement ports,
• measuring s-parameters at the measurement ports,
• correcting for systematic errors in said s-parameters based upon said error coefficients to yield a corrected S-parameter matrix, and
• shifting a reference plane for each element of said corrected S-parameter matrix to coincide with a measurement reference plane comprising modifying an argument of respective S-parameters according to respective ones of the shifted electrical lengths comprising
• adjusting each element of said corrected S-parameter matrix according to:
• Sdut=|ρ|e−j(θ0+δθ(f))
• wherein δθ is calculated from said electrical length as a function of frequency.

A method of measuring a DUT comprising the steps of:

• providing a vector network analyzer having at least two measurement ports,
• measuring a reflection characteristic of a high reflect calibration standard at each measurement port,
• measuring forward and reverse reflection and transmission characteristics of a line calibration standard,
• measuring forward and reverse reflection and transmission characteristics of a source terminated thru calibration standard,
• measuring forward and reverse reflection and transmission characteristics of a locally terminated thru calibration standard,
• calculating error coefficients for said at least two measurement ports based upon results in said steps of measuring,
• calculating a shifted electrical length attributable to said calibration standards based upon results in said steps of measuring by calculating a characteristic of said high reflect calibration standard, fitting an argument of said characteristic to a straight line, and using a slope of said straight line to calculate a shifted electrical length,
• connecting the DUT to the measurement ports,
• measuring s-parameters at the measurement ports,
• correcting for systematic errors in said s-parameters based upon said error coefficients to yield a corrected S-parameter matrix, and
• shifting a reference plane for each element of said corrected S-parameter matrix to coincide with a measurement reference plane.