RF3158PCBA-41X RFMD [RF Micro Devices], RF3158PCBA-41X Datasheet - Page 18

• Manufacturer Part Number: RF3158PCBA-41X
• Description: QUAD-BAND GSM/EDGE/GSM850/EGSM900 /DCS/PCS POWER AMPLIFIER MODULE
• Manufacturer: RFMD [RF Micro Devices]

RF3158
The V
tion. At some voltage below 0.35V, the CMOS controller switches off and turns off the PA. The effect of this is a discontinuity in
the response curve. In order to guarantee minimum switching transients, it is recommended that the minimum ramp voltage
be set slightly above the voltage where this discontinuity occurs (See Figure 3). The V
occurs is unique to the design of the part and does not shift significantly across process. Figure 3 shows the power versus
V
As the V
mum level, and the V
tional to the V
produce any higher output power. It is not recommended to apply a V
as the part could be damaged.
When the FET pass-device in the linear regulator saturates, the response time of the regulated voltage slows significantly. If the
control voltage changes (as in ramp-down) the saturated linear regulator does not react fast enough to follow the ramp-down
curve. The result is a discontinuity in the output power ramp and degraded switching transients. This usually occurs at low
V
circuit which senses if the FET pass-device is entering saturation and reduces V
the transceiver controller to adjust the maximum V
18 of 26
Figure 4. Output Power versus V
RAMP
BATT
RAMP
levels where the regulated V
response curve for two parts which represent typical process variation of the discontinuity.
RAMP
voltage range should be limited to min and max values in the specifications to avoid damage or undesirable opera-
voltage approaches its maximum, the linear regulator in the CMOS saturates, the output power reaches its maxi-
BATT
supply voltage applied. The V
RAMP
versus Output Power curve levels out. The saturation point of the linear regulator is directly propor-
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RAMP
CC
-15.0
-25.0
-35.0
35.0
25.0
15.0
-5.0
5.0
voltage is very near the supply voltage. The RF3158 incorporates a saturation detection
0.0
RAMP
0.5
RAMP
Low Band P
voltage can be increased above the saturation level, but the PA will not
824MHz, 3.6V, P
when the battery voltage is low.
1.0
V
RAMP
OUT
versus V
(V)
IN
1.5
=2dBm
RAMP
RAMP
voltage above the absolute maximum specification,
2.0
CC
Sample 1
Sample 2
to prevent it. This relieves the requirement of
2.5
RAMP
voltage at which the discontinuity
Rev A2 DS070615