AD8311 Datasheet, PDF (19/24 Pages) Analog Devices – 50 dB GSM PA Controller

Another way of presenting the error function of a log amp
detector is shown in Figure 40. In this case, the dB error at hot
and cold temperatures is calculated with respect to the transfer
function at ambient. This is a key difference in comparison to
the previous plots. Up to now, all errors have been calculated
with respect to the ideal transfer function at ambient.
When we use this alternative technique, the error at ambient
becomes by definition equal to 0 (see Figure 40).
This would be valid if the device transfer function perfectly
followed the ideal PIN = VSET / SLOPE + INTERCEPT equation.
However since a log amp in practice never perfectly follows this
equation (especially outside of its linear operating range), this
plot tends to artificially improve linearity and extend the
dynamic range. This plot is a useful tool for estimating
temperature drift at a particular power level with respect to the
(nonideal) response at ambient. However, achieving this level of
accuracy in an end application requires calibration at multiple
points in the device’s operating range.
AD8311
10
4
+85°C
+25°C
0
–40°C
3
–10
–20
–40°C
2
+85°C
1
–30
0
+25°C
–40
–1
–50
–60
0
–2
DOES NOT TAKE INTO ACCOUNT TRANSFER
FUNCTIONS’ NONLINEARITIES AT +25°C
–3
0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6
VSET (V)
Figure 40. Error vs. Temperature with respect to Output Voltage at 25 °C
DEVICE HANDLING
The wafer-level chip scale package consists of solder bumps
connected to the active side of the die. The part is lead-free with
95.5% tin, 4.0% silver, and 0.5% copper solder bump
composition. The WLCSP package can be mounted on printed
circuit boards using standard surface-mount assembly
techniques; however, caution should be taken to avoid
damaging the die. See the AN-617 application note for
additional information. WLCSP devices are bumped die, and
exposed die can be sensitive to light condition, which can
influence specified limits.
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