Instrumentation & Measurement Magazine 25-7 - 45

Table 1 - Comparison of test results and ATS measurement uncertainty
Parameter
IP Power
OP Power
Frequency Response
Group Delay
3rd
Noise Figure
Frequency
Translation Error
BOA Accuracy
ALC Accuracy
Spurious
Gain Stability
Output Power
Stability
Specification
-69 dBm
50 dBm
3.5 dB p-p (90%),
2.5 dB p-p (80%)
(small signal)
within mask
specification
order IMD (@3 dB
input back-off)
-11 dBc
3.5 dB
± 10 KHz
± 1 dB
± 1 dB
-60 dBc
2 dB p-p
1 dB p-p
Rack and Stack
method
-68.3 dBm
50.1 dBm
VNA method
-68.2 dBm
50.3 dBm
Measurement
uncertainty
(Rack and
Stack method)
± 0.4 dB
± 0.3 dB
1.5 dB p-p, 1 dB p-p 1.2 dB p-p, 0.8 dB p-p ± 0.2 dB p-p
within mask
-13.9 dB
2.8 dB
1.5 KHz
within ± 1 dB
within ± 1 dB
-68 dBc
0.6 dB
0.3 dB
brick wall response of the implemented filter in the spectrum
analyzer. To improve the measurement accuracy, three trace
values are averaged.
Input Drive: Input drive is measured by sweeping the stimulus
over a 20 dB amplitude range. This measurement also
requires uplink signal amplitude correction. To achieve accuracy
within 0.2 dB, 1001 points are chosen, as listed in Table 3.
Table 1 shows the numerical comparison for all the measured
parameters with the Rack and Stack method. It can be
seen that all of the parametric results show a close match for
both methods. The results are well within the integrated DUT
specifications. The characterization is repeated over multiple
sets of data, and a good match among the readings is obtained,
confirming the repeatability of the developed method.
ATS Measurement Uncertainty and
Time Estimation
The measurement uncertainty of ATS for all the measured
parameters is determined by taking 1000 samples of each parameter
over 24 hours and a span of seven days. The ± 3σ is
computed for each parameter. Table 1 shows the comparison
of measurement uncertainty using both systems for all parameters
considering the same number of points and bandwidth.
The results show that the measurement uncertainty and time
have improved using the developed method for specific parameters.
Table 2 compares measurement uncertainty for one
of the parameters (Input Power) considering the following
practical assumptions:
October 2022
within mask
-14.2 dBc
2.7 dB
2 KHz
within ± 1 dB
within ± 1 dB
-67 dBc
0.4 dB
0.2 dB
± 3 ns
± 0.1 dB
± 0.3 dB
± 100 Hz
± 0.2 dB
± 0.2 dB
± 0.4 dB
0.4 dB (max)
0.3 dB (max)
Measurement
uncertainty
(VNA
method)
± 0.3 dB
± 0.2 dB
± 0.2 dB p-p
± 2 ns
± 0.1 dB
± 0.2 dB
± 100 Hz
± 0.1 dB
± 0.1 dB
± 0.4 dB
0.4 dB (max)
0.3 dB (max)
◗ Mismatch Error (@ 15 dB return loss)
◗ Calibration error: Depending on calibration (scalar or
vector)
◗ Source power uncertainty
The performance of ATS is a trade-off between speed and
measurement uncertainty. The latter primarily governs it. A
comparison is shown between the conventional and the developed
method to estimate the time required to perform IO
Transfer Curve. IO Transfer Curve is done traditionally by
sweeping VSG in both power and frequency, and output is
measured on VSA. Experiments are carried out with various
sweep times, considering 1001 points, 100 kHz frequency
span, and 3 kHz resolution bandwidth to achieve ±0.2 dB
signal uncertainty. Table 3 shows that the overall optimum
measurement time for the developed method is only 10 seconds
compared to 25 seconds for the conventional approach
to achieve the same 0.2 dB generator uncertainty. The breakup
Table 2 - Measurement uncertainty
comparison (IP Power)
Rack and
Parameter
Mismatch
Scalar calibration
Source power
calibration
RSS
IEEE Instrumentation & Measurement Magazine
Stack method
± 0.14 dB
± 0.35 dB
± 0.2 dB
± 0.4 dB
VNA method
± 0.14 dB
± 0.21 dB
± 0.05 dB
± 0.3 dB
45
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