Test Results
Using the demoboard with the
The results highlight the excellent this supply voltage range, illus-
power control functionality trating that the ACPM-7891 can
Linear Technology IC, the results obtained by using the ACPM-7891 enable designs that meet GSM
shown in Table 4 were obtained.
in conjunction with a power loop
controller such as the LT1758.
Results are given for all three
bands, at four example power
level settings, with the supply
voltage at 3V, 3.6V and 4.3V. The
figures show that excellent power
output control is maintained over
transmitter specifications.
The LTC1758 RAMP signal is
generated from a DAC and a
simple single-pole filter is used
to shape the power ramp. The
input RF signal is based on the
GSM GMSK modulated signal.
Table 4. Results with variable Vdd and three point frequency ranges
GSM900
GSM5 (33 dBm)
GSM10 (23 dBm)
GSM15 (13 dBm)
GSM19 (5 dBm)
Frequency
Vdd
(V)
Vapc
(V)
Pout
(dBm)
Vapc
(V)
Pout
(dBm)
Vapc
(V)
Pout
(dBm)
Vapc
(V)
Pout
(dBm)
900 MHz
3.0
3.6
4.3
2.00
1.60
1.58
33.07
33.04
33.04
1.3
1.3
1.3
23.54
23.55
23.56
1.1
1.1
1.1
13.49
13.51
13.52
1.0
1.0
1.0
5.09
5.12
5.09
DCS1800
Frequency
1750 MHz
DCS0 (30 dBm)
DCS5 (20 dBm)
DCS10 (10 dBm)
DCS15 (0 dBm)
Vdd
(V)
Vapc
(V)
Pout
(dBm)
Vapc
(V)
Pout
(dBm)
Vapc
(V)
Pout
(dBm)
Vapc
(V)
Pout
(dBm)
3.0
3.6
4.3
2.0
1.7
1.7
30.35
30.32
30.28
1.3
1.3
1.3
20.20
20.17
20.14
1.1
1.1
1.1
10.42
10.40
10.37
1.0
1.0
1.0
0.08
0.06
0.06
PCS1900
Frequency
1880 MHz
PCS0 (30 dBm)
PCS5 (20 dBm)
PCS10 (10 dBm)
PCS15 (0 dBm)
Vdd
(V)
Vapc
(V)
Pout
(dBm)
Vapc
(V)
Pout
(dBm)
Vapc
(V)
Pout
(dBm)
Vapc
(V)
Pout
(dBm)
3.0
3.6
4.3
1.95
1.7
1.7
29.26
29.24
29.20
1.3
1.3
1.3
20.12
20.10
20.07
1.1
1.1
1.1
10.64
10.60
10.56
1.0
1.0
1.0
-0.04
-0.05
-0.09
19
HP [ HEWLETT-PACKARD ]
