MAX2235 Datasheet, PDF (1/8 Pages) Maxim Integrated Products – +3.6V, 1W Autoramping Power Amplifier for 900MHz Applications

19-1463; Rev 0; 5/99
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+3.6V, 1W Autoramping Power
Amplifier for 900MHz Applications
General Description
The MAX2235 low-voltage, silicon RF power amplifier
(PA) is designed for use in the 900MHz frequency band.
It operates directly from a single +2.7V to +5.5V supply,
making it suitable for use with 3-cell NiCd or 1-cell Li-Ion
batteries. The device delivers +30dBm (1W) typical out-
put power from a +3.6V supply or +28dBm from a +2.7V
supply.
The MAX2235’s gain is adjustable over a 37dB range.
A power-control pin controls gain and bias to maintain
optimum efficiency, even at lower output power levels,
thus extending the operating life of the battery. At
+30dBm output power, efficiency is typically 47%. An
additional power-saving feature is a shutdown mode
that typically reduces supply current below 1µA.
A key feature of this PA is its autoramping capability.
During turn-on and turn-off periods, the RF envelope is
controlled to approximate a raised cosine on the rising
and falling edge, thereby minimizing transient noise
and spectral splatter. The ramp time is set by selecting
the value of an external capacitor.
The MAX2235 is intended for use in constant envelope
applications such as AMPS, two-way paging, or FSK-
based communications in the 900MHz ISM band. The
device is available in a thermally enhanced 20-pin
TSSOP package with a heat slug.
Applications
900MHz ISM-Band Applications
Two-Way Pagers
Analog Cellular Phones
Microcellular GSM (Power Class 5)
Wireless Data Networks
Functional Diagram
RAMP ¹¹
REF ¹²
19
SHDN
20
GC
V_CC V_CC V_CC
4
35
BIAS
V_CC
8, 9
MAX2235
RFOUT
15, 16
Features
o 800MHz to 1000MHz Operation
o High Output Power at 836MHz
+32.5dBm at +5.0V
+30dBm at +3.6V
+29dBm at +3.0V
+28dBm at +2.7V
o +2.7V to +5.5V Single-Supply Operation
o Automatic Power-Up/Power-Down Ramp
o Direct On/Off Keying (OOK) without Intersymbol
Interference or VCO Pulling
o 37dB Power-Control Range
o 47% Efficiency
o <1µA Supply Current in Shutdown Mode
o Small 20-Pin TSSOP Package with Heat Slug
PART
MAX2235EUP
Ordering Information
TEMP. RANGE
-40°C to +85°C
PIN-PACKAGE
20 TSSOP-EP
Pin Configuration
TOP VIEW
RFIN 1
GND 2
V_CC 3
V_CC 4
V_CC 5
GND 6
GND 7
V_CC 8
V_CC 9
GND 10
MAX2235
20 GC
19 SHDN
18 GND
17 GND
16 RFOUT
15 RFOUT
14 GND
13 GND
12 REF
11 RAMP
RFIN ¹
VGA
2
GND
6, 7, 10
GND
13, 14, 17, 18, SLUG
GND
NOTE: SOLDER UNDERSIDE OF METAL SLUG TO BOARD GND PLANE.
TSSOP-EP
NOTE: THE GROUND OF THE OUTPUT STAGE IS CONNECTED TO THE
UNDERSIDE METAL SLUG.
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