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Professional Phones
Hands-free Sets
ISM Band Application
Wireless Infrastructure Preamplifiers
Description
The T0905 is a monolithic integrated power amplifier IC manufactured with Atmel鈥檚
Silicon-Germanium (SiGe) process. Due to its open architecture, the device can be
used either as a two or three-stage amplifier. Every stage can be matched individu-
ally, thus allowing applications in a wide frequency range. The T0905 can be used
from 135 MHz up to 600 MHz in both linear and non-linear (saturated) mode. The
power gain can be set dynamically by means of an analog control input optionally for
each single stage or for the entire power amplifier. Constant gain mode is also possi-
ble. The T0905 is suited for CW mode up to 35 dBm. These features, including wide
power ramp control, make the T0905 a very flexible power amplifier for many different
applications.
Apart from telephone applications, the T0905 can also be used for car identification
systems and several other wireless communication systems. The single supply volt-
age operation at +3.5 V and a negligible leakage current in power-down mode enable
a remarkable simplification of the application鈥檚 power management.
Figure 1.
Block Diagram
VCTL1
General-
purpose
VHF/UHF Power
Amplifier
(135 to 600 MHz)
T0905
Preliminary
GAIN1
16
VCTL2
GAIN2
VCTL3 GAIN3
15
Buf3
13
14
Buf2
17
18
19
VBIAS3
11
BGOUT
VCTL
VCC_CTL
12
10
BG
Buf1
9
8
20
VBIAS2
VB2_DC
VB3_DC
RFOUT/VCC3
7
RFIN1
21
GND3
Match
RF1
Match
RF2
Match
RF3
22-25
6
5
4
3
28
27
VB3
26
GND3
GND1 VCC1
GND2 VCC2
RFIN2
Rev. 4751D鈥揝IGE鈥?5/04