A920:
GSM TX VCO
Description
The VCO frequencies are 897 - 1880MHz, handling the three technology bands. The technology bands are controlled by MAGIC_LV via the data lines: N_BAND_0 and
N_BAND_1. CP_TX and GPO3 provides a dual port modulation mode for the TXVCO. N_BAND_0 and N_BAND_1 will select which VCO band will be activated.
GSM_EXC_EN and N_GSM_EXC_EN will enable the buffer stage of U570. TX_EN is activated prior to enabling the buffer and PA. TX_VCO_PRSC is fed back to the
MAGICLV for proper PLL operation. The output frequency for GSM is TX_VCO_LB and PCS / DCS is TX_VCO_HB. The charge pump output (CPTX) from
MAGIC_LV is the input (VT) for the VCO.
Motor
o
la
Conf
ide
n
tia
l Pr
opr
ie
ta
ry
4-
12
TX_VCO_PRSC
TX_VCO_HB
TX_VCO_LB
Tank
Ckt
CP_TX
Loop
Filter
Decoder
N_BAND_0
N_BAND_1
NB_TX_EN
Q700
MAGIC LV
POG
GPO3
GSM_EXC_EN
N_GSM_EXC_EN
RF_TOP
Section
SF_OUT
U700
TXVCO
Delay
FN
9 bit
Dual Port
D/A
GMSK
Look-up
Table
Pre-dist
Sys
Mux
DCS/PCS VCO
GSM VCO
