Figure 4 depicts the basic block
diagram of the ACPM-7891 PA
erence. The PCTL power control
pin is driven by a 10-bit DAC
control board, Figure 5 shows the and the DAC profile can be
control board layout, and Table 3 loaded via a serial port. The se-
details its bill of materials.
rial port data is stored in flash
memory which is capable of stor-
ing eight ramp profiles. The
The supporting LTC1758
demoboard is available upon
request from Linear Technology.
It has a 900 MHz and an
1800 MHz RF channel controlled
by the LTC1758. Timing signals
for TXEN are generated on the
board is supplied preloaded with
four GSM power profiles and
four DCS power profiles, cover-
ing the entire power range.
External timing signals can also
be used in place of the internal
board using a 13 MHz crystal ref- crystal controlled timing.
2.2 pF
220 pF
33 pF
68Ω
16
14
RFin
DCS/PCS
VAPC DCS/PCS Vdd3 DCS/PCS
VBATT
18
33 pF
DIRECTIONAL
COUPLER
RFin DCS/PCS
RFout DCS/PCS
DIPLEXER
11
33 pF
VCC
VIN
RF
50Ω
50Ω
RFout
VPCA
ACPM-7891
LTC1758
TXEN
PCTL
SHDN
SHDN
GND
TXEN
7
RFout EGSM
RFin EGSM
RFin EGSM
33 pF
DIRECTIONAL
COUPLER
26
VAPC EGSM
2
Vdd EGSM
4
33 pF
220 pF
2.2 pF
DAC
Figure 4. Block Diagram of the ACPM-7891 PA Control Board.
15
HP [ HEWLETT-PACKARD ]
