W3020 Datasheet, PDF (22/44 Pages) Agere Systems – GSM Multiband RF Transceiver

W3020 GSM Multiband RF Transceiver
Advance Data Sheet
December 1999
Programming Information (continued)
TR Register (continued)
B: Band Select
When set low, the GSM900 transceiver circuits are
enabled and the GSM1800 transceiver circuits are
disabled. When set high, the GSM1800 transceiver
circuits are enabled and the GSM900 transceiver
circuits are disabled. The transceiver circuits that
change with the setting of the band bit B are the LNA,
the RF mixer, the receive UHF LO1 buffer, the
transmit UHF LO1 buffer, and the LO2 divider for the
modulator IF LO phase shifter circuit. The normal LO2
division factor for GSM900 is divide-by-2; for
GSM1800, the normal LO2 division factor is divide-by-
3. Note that bits T2 and T1 also affect the transmitter
LO2 division factor when set high (see Table 23 and
Table 24).
Table 14. B: Band Select
B
Bit 23
0
1
Function
GSM900 Path On
GSM1800/1900 Path On
Note: When programmed via the same three-wire bus as
the W3000, updating this bit in W3020 also
updates it in W3000, and vice versa.
MO[3:1]: Mode Control
The various system modes of the W3020 are set by
the mode control bits. These are active in both the TR
and MAIN registers. The W3000 will also power up
with the W3020 in any of the valid modes set by the
mode bits in the TR or MAIN registers. The mode bit
settings for each W3020 system mode are given in
Table 15. The corresponding typical supply current for
the IC in each mode is shown in the Supply Currents
table on page 9.
In sleep mode, both the W3020 and W3000 are
powered down, and the supply current is in the µA
range. The transmit PLL settling mode is used prior to
a transmit burst in order to power up and lock the LO1
and LO2 VCO/PLL synthesizers and the respective
RF and IF LO buffers connecting to the modulator
circuit. The LO2 divide-by circuits remain off during
this mode. Similarly, the receive PLL settling mode is
used prior to the receive dc calibration time slot and
subsequent receive burst in order to power up and
lock the LO1 and LO2 VCO/PLL synthesizers and the
respective RF and IF LO buffers connecting to the RF
mixer and IF strip. The RF mixer can be turned on in
this mode by setting the C9 (RF mixer on during
settling) bit high in the CONFIG register (see Table
30). The transmitter ON mode turns on all the same
circuits as the transmit PLL settling mode along with
the I/Q modulator and up-conversion mixer.
The receiver ON mode turns on all the same circuits
as the receive PLL settling mode along, with the LNA
(if enabled by the G0 bit—see Table 26), RF mixer,
and IF amplifiers and demodulator. When first going
into receive mode, a baseband LP filter tune is
performed, if requested, by setting the FTR (filter tune
request) bit high in the TR register and the C6 (filter
tune disable) bit low in the CONFIG register (see
Table 20 and Table 35, respectively, and the Low-
Pass Filter Tuning section). Next, a dc offset
calibration cycle is performed if the DS (dc correction
skip) bit is low in the TR register and the C5 (dc
correction disable) bit is low in the CONFIG register
(see Table 22 and Table 36, respectively). The default
condition is that the LNA turns off during the dc
calibration if the C2 (LNA mode during dc calibration)
bit is low in the CONFIG register (see Table 37). The
other default condition is that the RF mixer LO1 buffer
turns off during the dc calibration if the C3 (RX LO1
buffer mode during dc calibration) bit is low in the
CONFIG register (see Table 38).
During this event, the transmit LO1 buffer will turn on
to act as a load stage for the UHF LO1 buffer. (For
additional information on the dc offset calibration, see
the dc Offset Correction Timing section.) After the dc
calibration cycle, all the receive circuits turn on as
mentioned above for the receive burst.
22
Lucent Technologies Inc.