lmh2120umx National Semiconductor Corporation, lmh2120umx Datasheet - Page 22

• Manufacturer Part Number: lmh2120umx
• Description: Lmh2120 6 Ghz Linear Rms Power Detector With 40 Db Dynamic Range
• Manufacturer: National Semiconductor Corporation

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Variation over Temperature Error
In contrast to the linear conformance error, the variation over
temperature error (E
temperature variation. The measured output voltage at 25°C
is subtracted from the output voltage at another temperature.
Subsequently, it is translated into an input referred error by
dividing it by K
temperature is given by:
The variation over temperature is shown in
dynamic range of 40 dB is obtained for E
1 dB Step Error
This parameter is a measure for the error for an 1 dB power
step. According to a 3GPP specification, the error should be
less than ±0.3 dB. This condition is often used to define a
useful dynamic range of the detector.
The 1 dB step error is calculated in 2 steps:
1.
2.
FIGURE 9. E
Determine the maximum sensitivity.
Calculate the 1 dB step error.
FIGURE 8. E
E
VOT
= (V
SLOPE
OUT_TEMP
VOT
LC
at 25°C. The equation for variation over
vs. RF input Power at 1900 MHz
VOT
vs. RF Input Power at 1900 MHz
) purely measures the error due to
- V
OUT 25°C
) / K
VOT
SLOPE
Figure
= ±0.5 dB.
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30055734
9, where a
(14)
22
First the maximum sensitivity (S
perature. It is defined as the maximum difference between
two output voltages for a 1 dB step within the power range:
The 1dB error is than calculated by:
where S
two output voltages for a 1 dB step at a given power level.
Figure 10
where a dynamic range of 36 dB over temperature is obtained
for E
10 dB step error
This error is defined in a different manner than the 1 dB step
error. This parameter shows the input power error over tem-
perature for a 10 dB power step. The 10 dB step at 25°C is
taken as a reference.
To determine the 10 dB step error first the output voltage lev-
els (V1 and V2) for power levels “P” and “P+10dB” at the
25°C are determined
put voltages are used to determine the corresponding power
levels at temperature T (P
tween those two power levels minus 10 results in the 10 dB
step error.
FIGURE 10. 1 dB Step Error vs. RF Input Power at 1900
1dB
= ±0.3 dB.
ACTUAL
shows the typical 1 dB step error at 1900 MHz,
E
1 dB
S
(actual sensitivity) is the difference between
MAX
= (S
= V
ACTUAL
(Figure
OUT P+1
T
MHz
- S
and P
11). Subsequently these 2 out-
MAX
- V
MAX
OUT P
) / S
T
+X). The difference be-
) is calculated per tem-
MAX
30055738
(15)
(16)