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3. HW Circuit Description
The digital transmitter architecture is based on a fractional-N sigma-delta synthesizer for constant
envelope GMSK modulation. This configuration allows a very low power design with a reduced
external component count.
The modulation is transferred between baseband- and RF-part of the PMB7880 via a digital interface
signal into the digital modulator. The following Gaussian filter shapes the digital data stream for the
GMSK modulation. Additionally a pre-distortion filter compensates the attenuation of the PLL transfer
function resulting in a very low distortion at the transmit output. The filtered digital data stream is
scaled appropriately and added to the channel word.
This sum is fed into the MASH modulator. The output of the MASH modulator is a sequence of integer
divider values representing the high resolution fractional input signal. This sequence controls the MMD
(multi modulus divider) at a sample rate of 26MHz. Thus a tightly controlled frequency modulation of
the VCO is achieved.
LGE Internal Use Only
Copyright © 2008 LG Electronics. Inc. All right reserved.
Only for training and service purposes
Figure 3-9-2. PAM (Power Amplifier Module) interface
close to DBB
0.5p
C415
3.3nH
L400
0.01u
C407
47
R404
DNI
C418
ECCH0003002
C405
C2012JF1A106ZT
10u
C419
DNI
1.5p
C402
47
R405
R400
15K
GND8
14
GND9
16
21
P_GND
19
RSVD_GND
VAPC
20
17
VBATT
2
VCC1A
6
VCC1B
BS
1
DCS_PCS_IN
3
15
DCS_PCS_OUT
4
EGSM_IN
11
EGSM_OUT
ENABLE
18
GND1
5
7
GND2
8
GND3
GND4
9
10
GND5
GND6
12
13
GND7
C400
SKY77318
U400
68p
C412
180p
C410
15p
47p
C413
C421
0.5p
27p
C423
1.5p
C422
0.5p
C403
C417
1p
1.5p
C414
L410
2.7nH
0.01u
C408
0.01u
VBAT
10nH
L404
C406
R403
10
39p
C409
VDDRF1
18nH
L403
1nH
L401
3.3nH
L411
2.2p
C401
TXLB
TXHB
TX_RAMP
PA_BAND
PA_EN
Содержание KP151Q
Страница 1: ...Service Manual Model KP151Q Service Manual KP151Q Date September 2008 Issue 1 0 Internal Use Only ...
Страница 107: ... 108 LGE Internal Use Only Copyright 2008 LG Electronics Inc All right reserved Only for training and service purposes ...
Страница 127: ...Note ...
Страница 128: ...Note ...