3.26.1 Dual Mode Operation
When VMODE is low, the voltage on VRAMP is used to regulate the PA collector voltage which
directly controls the output power. When VMODE is high, the PA collector voltage is regulated to
3.6V, and the supply for the PA base bias can be adjusted via the VRAMP pin to optimize current
drain for low or high power ranges. In addition, in 8PSK mode, the first stage of the low band PA is
bypassed to decrease gain, but in high band, the PA operates with all stages.
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3. TECHNICAL BRIEF
PIN Function Description
1 HB_RFIN RF input to the High-band PA
2 BAND_SEL Logic low=low band, Logic high=high band select
3 TX_EN PA Enable
4 VBATT Main supply
5 VMODE Logic low=GMSK mode, Logic high=8PSK mode select
6 VRAMP Ramped burst pin
7 LB_RFIN RF input to the Low-band PA
8,9,10,11 GND Ground
12 LB_RFOUT RF output from the low-band PA
13,14,15,16,17 GND
18 HB_RFOUT RF output from the high-band PA
19,20,21,22,23 GND
MODE VMODE RF INPUT VRAMP TX ENABLE
GSM Low Fixed Ramp Burst Control High
EDGE High Ramp Burst Control Control amp bias current High
Table 13 PAM pin description
Figure 42 PAM schematic
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