LG KE 770, Руководство по обслуживанию

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3. TECHNICAL BRIEF
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3.24. Power Amplifier Module
The RF3158 (U501) is a high-power, dual-mode amplifier (PA) with integrated power control. This PA
is designed to operate both in a saturated mode for GMSK signaling and in a linear mode for 8PSK
modulation. Featuring input and output terminals that are internally matched to 50 ohms, the PAM is
designed to be the final amplification stage in a dual-mode GSM/EDGE mobile transmit lineup
operating in the 824 MHz to 915 MHz (low) and 1710 MHz to 1910 MHz (high) bands.
3.24.1 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.
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