Power Amplifier; Mhz Clock - LG MG180C Service Manual

3. H/W Circuit Description

3.3.1. Power Amplifier

The RF3166 [U500] is a quad-band EGSM 900/GSM 850/DCS/PCS power amplifier module that
incorporat es an indirect closed loop method of power control. The indirect closed loop is fully self-
contained and it do es not require loop optimization. It can be driven directly from the DAC output in
the baseband circuit. On-board power control provides over 37 dB of control range with an analog
voltage input(Vramp). Efficien cy is 60% at GSM and 55% at DCS/PCS.

3.3.2. 26MHz Clock

The 26 MHz clock consists of a TCXO(Temperature Compensated Crystal Oscillator) which oscillates
at a frequency of 26 MHz. It is used within the Si4210 RF Main Chip, BB Analog chip-set(IOTA), Digita
l chip-set(Calypso-).
AFC
X500 26MHz
R515
1 3
VCONT OUT
12K
2 4
GND VCC
C532
1000p
Figure 5. VC-TCXO Circuit
- 18 -
RF2.85V
TCXO_OUT
C530
1000p
C531
1uF