General Description

The MAX2235 low-voltage, silicon RF power amplifier (PA)

is designed for use in the 900MHz frequency band. It oper-

ates 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 output 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

Features

● 800MHz to 1000MHz Operation

● High Output Power at 836MHz

• +32.5dBm at +5.0V

• +30dBm at +3.6V

• +29dBm at +3.0V

• +28dBm at +2.7V

● +2.7V to +5.5V Single-Supply Operation

● Automatic Power-Up/Power-Down Ramp

● Direct On/Off Keying (OOK) without Intersymbol

Interference or VCO Pulling

● 37dB Power-Control Range

● 47% Efficiency

● <1μA Supply Current in Shutdown Mode

● Small 20-Pin TSSOP Package with Heat Slug

19-1463; Rev 3; 8/21

PART

TEMP. RANGE

PIN-PACKAGE

MAX2235EUP

-40°C to +85°C

20 TSSOP-EP

+3.6V, 1W Autoramping Power

Amplifier for 900MHz Applications

MAX2235

Evaluation Kit

Available

Design

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and Models

Support

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Tel: 781.329.4700

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Functional Diagram

Pin Configuration

Ordering Information

MAX2235

SHDN

GC

RFIN

RAMP

BIAS

VCC

VCC VCC

VCC

REF

NOTE: SOLDER UNDERSIDE OF METAL SLUG TO BOARD GND PLANE.

RFOUT

GND

GND

GND

15, 16

6, 7, 10

2

1

11

4

3

5

8, 9

12

19

20

13, 14, 17, 18, SLUG

VGA

20

19

18

17

16

15

14

13

1

2

3

4

5

6

7

8

GC

SHDN

GND

GND

VCC

VCC

GND

RFIN

TOP VIEW

RFOUT

RFOUT

GND

GND

VCC

GND

GND

VCC

12

11

9

10

REF

RAMP

GND

VCC

MAX2235

+

TSSOP-EP

NOTE: THE GROUND OF THE OUTPUT STAGE IS CONNECTED TO THE

UNDERSIDE METAL SLUG.