User Guide

PAMS Technical Documentation System Module & UI
NHM-8NX
Issue 1 05/02 ãNokia Corporation Page 71
Functional descriptions
RF block diagram
Block diagrams of direct conversion receiver and transmitter RF section has described in
the following figure.
The architecture is based on Mjoelner, the RF ASIC, which contains most of the function-
ality of the RF Engine. The ASIC contains RX and TX functions, VCXO (crystal is placed
external to the ASIC), se the block diagram.
Figure 26: Block Schematic
Frequency synthesizers
VCXO
The VCXO is an on-chip oscillator with off-chip crystal. The oscillator in itself is balanced
with two independent outputs. One output is used inside the ASIC as reference for the
PLL. The second output is for the baseband, an output which can be filtered inside the
ASIC, controlled by SW. The reference frequency is 26 MHz in order to ease the suppres-
sion of the reference spurious.
The drive level of the crystal can be adjusted by software control, also the frequency
accuracy is controlled by software with a digital frequency inputs. The digital frequency
control is divided between calibration and AFC.
VCO
The VCO is module containing all the frequency determining parts inside. The VCO covers
64/65
NDIV
ADIV
ϕ
charge
pump
RDIV
1/2
1/4
CPOUT
2
222
1/2 1/4
DET
loop
filter
26MHz
INPL
INML
INPM
INMM
OUTHP
OUTHM
OUTLP
OUTLM
RXQP
RXIP
Open
collector
Open
collector
LPF1
DCN1
PWC
DET
RBEXT
RF
Controls
RF
Controls
VANT1 / VANT2
VXO
BBAMP
BBAMP
SAW
SAW
PA
Dir. Coupler
TXC
TXP
RESET_X
Ant Switch
RX
RX
TX
TX
PCN
GSM
VBATT
V
D
D
R
X
B
B
Mjoelner
PCN
EGSM
VTXBL VTXBH
VTXLOL
Buffer
VBEXT
VRX
INPH
INMH
AGC
LOCNT
REFCNT
Lock
detect
TXIP/TXIM
TXQP/TXQM
2
2
2
2
2 2 2 2
XTALM
XTALP
REFOU
T
2
2
LPF2
RXIM
LPF1
DCN1
AGC
LPF2
RXQM
2
PW-
loop
Filter
PLFB1
PLFB2
VPCH/VPCL
2
VPLL
VDDCP
VDDPRE
LO
buffer
VDDLO
VDDPLL
V
D
D
R
X
F
VDDXO
VREF1
VDDDL
VDDDIG
VDDBBB
VBB
SAW
SAW
CTRL
VTX
VTX
RX900
RX1800
RX1900
BIQUAD
BIQUAD
2,7k
DCN2
DCN2
TXC
TXP
SENSE
VCP
RESETX
VCCVCO1
VCCVCO2
VVCO
VDDTX
Hitachi PA: 18k
RFMD PA: 82k
REFOUT
RFBUSCLK
RFBUSX
RFBUSDA
3