U2042XA Datasheet, PDF (22/25 Pages) Keysight Technologies – U2040 X-Series Wide Dynamic Range Power Sensors

22 | Keysight | U2040 X-Series Wide Dynamic Range Power Sensors – Data Sheet
Worked example for U2041XA
Uncertainty calculations for a power measurement (settled, average power)
(Specification values from this document are in bold italic, values calculated on this page are underlined.)
Process:
1. Power level: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
2. Frequency:. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3. Calculate sensor uncertainty: In Free Run, auto zero mode average = 1
Calculate noise contribution, assuming 50 ms aperture (default)
– If in Free Run mode, Noise = Measurement noise x free run multiplier = 80 pW x 4.0 = 0.32 nW
– If in Trigger mode, Noise = Noise-per-sample x noise per sample multiplier
Convert noise contribution to a relative term ¹ = Noise/Power = 0.32 nW / 1 mW = 0.000032%,
value clipped to 0.01%
Convert zero drift to relative term = Drift/Power = 25 pW / 1 mW . . . . . . . . . . . . . . . . . . . . . . . .
RSS of above terms = . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
4. Zero uncertainty
(Mode and frequency dependent) = Zero set/Power = 70 pW / 1 mW. . . . . . . . . . . . . . . . . . . . . .
5. Sensor calibration uncertainty
(Sensor, frequency, power and temperature dependent) =. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
6. System contribution, coverage factor of 2 ≥ sys_rss =. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
(RSS three terms from steps 3, 4 and 5)
7. Standard uncertainty of mismatch
Max SWR (frequency dependent) =. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Convert to reflection coefficient, | r_Sensor | = (SWR–1)/(SWR+1) = . . . . . . . . . . . . . . . . . . . . . . . . . . .
Max DUT SWR (frequency dependent) =. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Convert to reflection coefficient, | r_DUT | = (SWR–1)/(SWR+1) = . . . . . . . . . . . . . . . . . . . . . . . . . . . .
8. Combined measurement uncertainty @ k = 1
( ) ( ) ( ) ( ) ^UC ⁼
—^M——^a—^x—(^r—^D—^U—^T—⁾ —^• —^M—^a——^{x (—r}—^S—^e—^ns—^o—^r)
√2
2 _{+ —s—y—s—rs—s} 2
2
U_C =
0.091 • 0.155 ² 0.037 ²
—————————— + —————
√2
2
Expanded uncertainty, k = 2, = U_C • 2 = . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
1 mW
1 GHz
0.01%
0.0000025%
0.01%
0.000007%
3.7%
3.7%
1.20
0.091
1.26
0.115
1.99%
3.98%
1.  The noise to power ratio for average only mode is capped at 0.01% for measurement uncertainty calculation purposes.