Agilent Technologies Z5623A manual Setting Test Limits, Equation 5-1 How to Set Test Limits

Performance Verification

Setting Test Limits

Setting Test Limits

A test limit is the pass/fail criterion for a measurement. A test limit can be either a maximum limit or a minimum limit. With a maximum limit, the measurement must not go above the limit in order for the Device Under Test (DUT) to pass. With a minimum limit, the measurement must not go below the limit in order for the DUT to pass.

Test limits are derived from the specifications of the DUT, but are usually different from them because every measurement has some uncertainty associated with it. In order to ensure that a performance specification is met, a “guard band” must be added to account for the uncertainty in the measurement. This can be done by applying Equation 5-1.

Equation 5-1 How to Set Test Limits

Test Limit = Specification ± Measurement Uncertainty

In Equation 5-1, the plus sign is selected if the limit is a minimum limit, and the minus sign is selected if the limit is a maximum limit. For example, if a specification is 20 dB minimum and the measurement uncertainty is 2 dB, then the test limit should be set to 22 dB. In other words, the measured value in this example must be 22 dB or greater to insure that the actual value is 20 dB or greater. Similarly, if a specification is 20 dB maximum and the measurement uncertainty is 2 dB, then the test limit should be set to 18 dB. In other words, the measured value in this example must be 18 dB or less to insure that the actual value is 20 dB or less.

The measurement uncertainties listed in Table 5-1apply to the performance tests described in this document. The uncertainties are derived from the equipment used and the specific measurements performed.

Table 5-1		Measurement Uncertainties for Performance Verification Tests
	Measurement	Band 1	Band 2	Band 3	Band 4
	(dB)	(300 kHz - 1.3 GHz)	(1.3 - 3 GHz)	(3 - 6 GHz)	(6 - 9 GHz)
	Crosstalk	5	5	5	7
	Return Loss	1.5	1.0	0.5	0.5
	(port active)
	Return Loss	1.5	1.5	1.0	0.5
	(port off)
	Insertion Loss	0.3	0.3	0.3	0.3

5 -2 Agilent Technologies Z5623A Option H48