MAXIM MAX2235 Technical data

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 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 FSK­based 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

MAX2235

+3.6V, 1W Autoramping Power

Amplifier for 900MHz Applications

________________________________________________________________ Maxim Integrated Products 1

Functional Diagram

19-1463; Rev 2; 10/00

PART

MAX2235EUP -40°C to +85°C

TEMP. RANGE PIN-PACKAGE

20 TSSOP-EP

EVALUATION KIT

AVAILABLE

Pin Configuration

Ordering Information

For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct! at
1-888-629-4642, or visit Maxim’s website at www.maxim-ic.com.

V

CCVCCVCC

4 3 5 8, 9

11

RAMP

12

REF

SHDN

GC

RFIN

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

BIAS

19

20

1

VGA

V

CC

MAX2235

6, 7, 102

RFOUT

15, 16

13, 14, 17, 18, SLUG

GNDGND GND

TOP VIEW

1

RFIN

2

GND

3

V

CC

4

CC

5

6

7

8

9

10

MAX2235

TSSOP-EP

V

CC

GND

GND

CC

V

CC

NOTE: THE GROUND OF THE OUTPUT STAGE IS CONNECTED TO THE
UNDERSIDE METAL SLUG.

20

GC

19

SHDN

18

GND

17

GNDV

16

RFOUT

15

RFOUT

14

GND

13

GNDV

12

REF

11

RAMPGND

MAX2235

+3.6V, 1W Autoramping Power
Amplifier for 900MHz Applications

2 _______________________________________________________________________________________

ABSOLUTE MAXIMUM RATINGS

DC ELECTRICAL CHARACTERISTICS

(VCC= +2.7V to +5.5V, GC = RAMP = REF = unconnected, no input signal applied, TA= -40°C to +85°C, unless otherwise noted.
Typical values are at V

CC

= +3.6V and TA= +25°C.)

Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional
operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to
absolute maximum rating conditions for extended periods may affect device reliability.

VCCto GND...........................................................-0.3V to +6.5V

SHDN to GND.............................................-0.3V to (V

CC

+ 0.3V)

GC to GND .................................................-0.3V to (V

CC

+ 0.3V)

RF Input Power .................................................+13dBm (20mW)

Maximum Load Mismatch without Damage,

V

CC

= +2.7V to +3.4V, Any Load Phase Angle,

Any Duration.......................................................................20:1

Maximum Load Mismatch without Damage,

V

CC

= +3.4V to +5.5V, Any Load Phase Angle,

Any Duration.........................................................................8:1

Continuous Power Dissipation (T

A

= +70°C)

TSSOP (derate 80mW/°C above T

A

= +70°C) ..................6.4W

Operating Temperature Range ...........................-40°C to +85°C

Junction Temperature......................................................+150°C

Storage Temperature Range .............................-65°C to +150°C

Lead Temperature (soldering, 10s) .................................+300°C

SHDN = GND

(Note 1)

(Note 2)

V

SHDN

> 2.3V, VGC> 0.6V

V

SHDN

< 0.5V, VGC< 0.4V

2.7V < VCC< 3.4V, SHDN = GND,
T

A

= +55°C

V

SHDN

= 2.0V

V

SHDN

< 0.5V

CONDITIONS

0.5 100

V0.5V

IL

V2.0V

IH

SHDN Logic High
SHDN Logic Low

V2.0 2.2 2.4V

GCNOM

GC Open-Circuit Voltage

µA

-10 1.0

I

GC

GC Input Current

-0.5 0.5

I

SHDN

Shutdown Supply Current µA

2

0.5
µA

-0.5 0.5

I

INSHDN

SHDN Input Current

UNITSMIN TYP MAXSYMBOLPARAMETER

VGC< 0.4 mA20I

STBY

Standby Supply Current

MAX2235

+3.6V, 1W Autoramping Power

Amplifier for 900MHz Applications

_______________________________________________________________________________________ 3

Note 1: ≥ +25°C guaranteed by production test, <+25°C guaranteed by design and characterization.
Note 2: MAX guaranteed by production test, MIN guaranteed by design and characterization.
Note 3: Guaranteed by design and characterization.
Note 4: For optimum performance at a given frequency, design the output matching network for maximum output power.
Note 5: Gain is monotonic with V

GC

.

Note 6: 0.068µF capacitor from RAMP to REF. Time is measured from SHDN low-to-high transition to +29dBm output power, or

from SHDN high-to-low transition to -25dBm output power.

Note 7: Harmonics measured on the evaluation kit, which provides some harmonic attenuation in addition to the rejection provided

by the IC. The combined suppression is specified.

P

RFIN

adjusted to give P

RFOUT

= +24dBm

P

RFOUT

= +30dBm

P

RFIN

= 0dBm, VGCadjusted to give

P

RFOUT

= 24dBm

315

610

Average Supply Current

%47PAEPower Added Efficiency

0.6V < VGC< 2.3V dB37

dB24 26G

P

Power Gain

Gain-Control Range (Note 5)

mW/µs1.6dP/dt

Auto-Power Ramping-Up
Maximum Slope (Note 6)

Input VSWR relative to input impedance in
operating mode

VCC= 2.7V to 5.5V, 6:1 VSWR at any phase
angle

1.5:1∆VSWR

Standby Mode Input VSWR
Change

50Ω source impedance

dBc-60

Maximum Nonharmonic
Spurious Output Due to Load
Mismatch

1.5:1VSWRInput VSWR

mW/µs-1.3dP/dt

Auto-Power Ramping-Down
Minimum Slope (Note 6)

30kHz BW at offset = 45MHz dBm-90Noise Power

40 48

P

RFIN

= +7dBm dBc30 38Harmonic Suppression (Note 7)

mA

305

I

CC

P

RFIN

= 0dBm dB

25 36

Off-Isolation

V

SHDN

= 0.5V

GC = GND

AC ELECTRICAL CHARACTERISTICS

(MAX2235 Evaluation Kit, GC = unconnected, P

RFIN

adjusted to give P

RFOUT

= +30dBm, f

RFIN

= 836MHz, VCC= V

SHDN

= +3.6V,

T

A

= +25°C, unless otherwise noted.) (Note 3)

CONDITIONS UNITSMIN TYP MAXSYMBOLPARAMETER

VCC= 2.7V 28.0

VCC= 3.0V, TA= T

MIN

to T

MAX

25.5

VCC= 3.0V (Note 4)

27.0 28.7

VCC= 3.6V

30.3

VCC= 5.0V

dBm

32.5

P

RFOUT

Minimum Output Power

MHz

800 1000

f

RFIN

Operational Frequency Range
(Note 4)