19-1185; Rev 3; 9/08
KIT
ATION
EVALU
E
BL
AVAILA
3.6V, 1W RF Power Transistors
for 900MHz Applications
____________________________Features
♦
Low Voltage: Operates from 1 Li-Ion or
3 NiCd/NiMH Batteries
♦
DC-to-Microwave Operating Range
♦
1W Output Power at 900MHz
♦
On-Chip Diode for Accurate Biasing (MAX2602)
♦
Low-Cost Silicon Bipolar Technology
♦
Does Not Require Negative Bias or Supply Switch
♦
High Efficiency: 58%
General Description
The MAX2601/MAX2602 are RF power transistors opti-
mized for use in portable cellular and wireless equipment
that operates from three NiCd/NiMH cells or one Li-Ion
cell. These transistors deliver 1W of RF power from a
3.6V supply with efficiency of 58% when biased for con-
stant-envelope applications (e.g., FM or FSK). For NADC
(IS-54) operation, they deliver 29dBm with -28dBc ACPR
from a 4.8V supply.
The MAX2601 is a high-performance silicon bipolar RF
power transistor. The MAX2602 includes a high-
performance silicon bipolar RF power transistor, and a
biasing diode that matches the thermal and process
characteristics of the power transistor. This diode is
used to create a bias network that accurately controls
the power transistor’s collector current as the tempera-
ture changes.
The MAX2601/MAX2602 can be used as the final stage
in a discrete or module power amplifier. Silicon bipolar
technology eliminates the need for voltage inverters
and sequencing circuitry, as required by GaAsFET
power amplifiers. Furthermore, a drain switch is not
required to turn off the MAX2601/MAX2602. This
increases operating time in two ways: it allows lower
system end-of-life battery voltage, and it eliminates the
wasted power from a drain-switch device.
The MAX2601/MAX2602 are available in thermally
enhanced, 8-pin SO packages, which are screened to
the extended temperature range (-40°C to +85°C).
MAX2601/MAX2602
Ordering Information
PART
MAX2601ESA
MAX2602ESA
TEMP RANGE
-40°C to +85°C
-40°C to +85°C
PIN-PACKAGE
8 SOIC
8 SOIC
________________________Applications
Narrow-Band PCS (NPCS)
915MHz ISM Transmitters
Microcellular GSM (Power Class 5)
AMPS Cellular Phones
Digital Cellular Phones
Two-Way Paging
CDPD Modems
Land Mobile Radios
C
E
E
B
1
2
3
4
8
7
6
5
Pin Configurations
TOP VIEW
C
E
E
B
C
E
BIAS
B
1
2
3
4
8
7
6
5
C
E
E
B
MAX2601
PSOPII
MAX2602
PSOPII
Typical Application Circuit appears at end of data sheet.
________________________________________________________________
Maxim Integrated Products
1
For pricing, delivery, and ordering information, please contact Maxim Direct at 1-888-629-4642,
or visit Maxim’s website at www.maxim-ic.com.
3.6V, 1W RF Power Transistors
for 900MHz Applications
MAX2601/MAX2602
ABSOLUTE MAXIMUM RATINGS
Collector-Emitter Voltage, Shorted Base (V
CES
) ....................17V
Emitter Base Reverse Voltage (V
EBO
)...................................2.3V
BIAS Diode Reverse Breakdown Voltage (MAX2602) ..........2.3V
Average Collector Current (I
C
)........................................1200mA
Continuous Power Dissipation (T
A
= +70°C)
SOIC (derate 80mW/°C above +70°C) (Note 1) .............6.4W
Operating Temperature Range ...........................-40°C to +85°C
Storage Temperature Range .............................-65°C to +165°C
Junction Temperature ......................................................+150°C
Lead Temperature (soldering, 10s) .................................+300°C
Note 1:
Backside slug must be properly soldered to ground plane (see
Slug Layout Techniques
section).
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.
DC ELECTRICAL CHARACTERISTICS
(T
A
= T
MIN
to T
MAX
, unless otherwise noted.)
PARAMETER
Collector-Emitter Breakdown
Voltage
Collector-Emitter Sustaining
Voltage
Collector-Base Breakdown
Voltage
DC Current Gain
Collector Cutoff Current
Output Capacitance
SYMBOL
BV
CEO
BV
CES
LV
CEO
BV
CBO
h
FE
I
CES
C
OB
I
C
< 100µA
I
C
= 200mA
I
C
< 100µA, emitter open
I
C
= 250mA, V
CE
= 3V
V
CE
= 6V, V
BE
= 0V
V
CB
= 3V, I
E
= 0mA, f = 1MHz
CONDITIONS
Open base
Shorted base
MIN
15
15
5.0
15
100
0.05
9.6
1.5
µA
pF
TYP
MAX
UNITS
V
V
V
AC ELECTRICAL CHARACTERISTICS
(Test Circuit of Figure 1, V
CC
= 3.6V, V
BB
= 0.750V, Z
LOAD
= Z
SOURCE
= 50Ω, P
OUT
= 30dBm, f = 836MHz, T
A
= +25°C, unless oth-
erwise noted.)
PARAMETER
Frequency Range
Base Current
Harmonics
Power Gain
Collector Efficiency
Stability under Continuous
Load Mismatch Conditions
Two-Tone IMR
Noise Figure
η
V
SWR
IM3
IM5
NF
SYMBOL
f
I
B
2fo, 3fo
V
CC
= 3.6V, P
OUT
= 30dBm
V
CC
= 3.0V, P
OUT
= 29dBm
P
OUT
= 30dBm
No modulation
V
CC
= 5.5V, all angles (Note 3)
P
OUT
= +30dBm total power, f1 = 835MHz,
f2 = 836MHz
V
BB
= 0.9V
(Note 2)
CONDITIONS
MIN
DC
4.2
-43
-42
11.6
58
8:1
-16
-25
3.3
dBc
dB
TYP
MAX
1
UNITS
GHz
mA
dBc
dBc
dB
%
Note 2:
Guaranteed by design.
Note 3:
Under these conditions: a) no spurious oscillations shall be observed at collector greater than -60dBc; b) no parametric
degradation is observable when mismatch is removed; and c) no current draw in excess of the package dissipation
capability is observed.
2
_______________________________________________________________________________________
3.6V, 1W RF Power Transistors
for 900MHz Applications
__________________________________________Typical Operating Characteristics
(Test Circuit of Figure 1, input/output matching networks optimized for specific measurement frequency, V
CC
= 3.6V, V
BB
= 0.750V,
P
OUT
= 30dBm, Z
LOAD
= Z
SOURCE
= 50Ω, f = 836MHz, T
A
= +25°C, unless otherwise noted.)
TWO-TONE OUTPUT POWER AND IM3
vs. COLLECTOR CURRENT
MAX2601-02
MAX2601-01
MAX2601/MAX2602
COLLECTOR CURRENT
1.0
31
TWO-TONE OUTPUT POWER, IM3, IM5
vs. INPUT POWER
P
OUT
, IM3, AND IM5
ARE RMS COMPOSITE
TWO-TONE POWER
LEVELS
P
OUT
MAX2601-03
20
0.8
V
BB
= 1.00V
V
BB
= 0.95V
V
BB
= 0.90V
P
OUT
(dBm)
P
OUT
, IM3, AND IM5
ARE RMS COMPOSITE
TWO-TONE POWER LEVELS
30
35
P
OUT
I
CC
(A)
0.6
P
OUT
, IM3, IM5 (dBm)
19
25
29
IM3
28
18
15
IM3
0.4
17
0.2
5
IM5
V
BB
= 0.85V
V
BB
= 0.80V
27
6
0.4
0.5
0.6
I
CC
(A)
0.7
0.8
16
-5
5
10
15
INPUT POWER (dBm)
20
25
0
0
1
2
3
V
CE
(V)
4
5
TWO-TONE OUTPUT POWER, IM3, IM5
vs. INPUT POWER (f = 433MHz)
MAX2601-04
ACPR vs. OUTPUT POWER
(IS-54
π/4
DQPSK MODULATION, V
BB
= 0.85V)
MAX2601-05
COLLECTOR EFFICIENCY vs. OUTPUT POWER
(IS-54
π/4
DQPSK MODULATION, V
BB
= 0.85V)
P
OUT
, IM3, AND IM5
ARE RMS COMPOSITE
TWO-TONE POWER
LEVELS
3.0V
MAX2601-06
35
P
OUT
25
P
OUT
, IM3, AND IM5
ARE RMS COMPOSITE
TWO-TONE
POWER LEVELS
-20
-22
-24
3.0V
60
50
EFFICIENCY (%)
40
30
20
4.8V
10
0
P
OUT
, IM3, IM5 (dBm)
-26
ACPR (dBc)
IM3
-28
-30
-32
-34
-36
-38
4.8V
4.2V
3.6V
15
3.6V
4.2V
IM5
5
-5
5
10
15
INPUT POWER (dBm)
20
25
-40
10
15
20
25
30
35
OUTPUT POWER (dBm)
10
15
20
25
30
35
OUTPUT POWER (dBm)
______________________________________________________________Pin Description
PIN
NAME
MAX2601
1, 8
2, 3, 6, 7, Slug
MAX2602
1, 8
2, 6, 7, Slug
C
E
Transistor Collector
Transistor Emitter
Anode of the Biasing Diode that matches the thermal and process char-
acteristics of the power transistor. Requires a high-RF-impedance, low-
DC-impedance (e.g., inductor) connection to the transistor base (Pin 4).
Current through the biasing diode (into Pin 3) is proportional to 1/15 the
collector current in the transistor.
Transistor Base
3
FUNCTION
—
3
BIAS
4, 5
4, 5
B
_______________________________________________________________________________________
3.6V, 1W RF Power Transistors
for 900MHz Applications
MAX2601/MAX2602
V
CC
V
BB
0.1μF
1000pF
100nH
24Ω
1
4
RF
IN
T1
1000pF
5
2pF
12pF
2, 6, 7
BACKSIDE
SLUG
8
10pF
1000pF
T2
5Ω
1000pF
L1
0.1μF
2pF
L1 = COILCRAFT A05T INDUCTOR, 18.5nH
T1, T2 = 1", 50Ω TRANSMISSION LINE ON FR-4
Figure 1. Test Circuit
_______________Detailed Description
MAX2601/MAX2602
The MAX2601/MAX2602 are high-performance silicon
bipolar transistors in power-enhanced, 8-pin SO pack-
ages. The base and collector connections use two pins
each to reduce series inductance. The emitter connects
to three (MAX2602) or four (MAX2601) pins in addition
to a back-side heat slug, which solders directly to the
PC board ground to reduce emitter inductance and
improve thermal dissipation. The transistors are intend-
ed to be used in the common-emitter configuration for
maximum
power
gain
and
power-added
efficiency.
V
CC
V
CC
R
BIAS
RF
C
RF
OUT
C
OUT
RF
C
Q1
C
BIAS
C
IN
RF
IN
Q2
Current Mirror Bias
(MAX2602 only)
The MAX2602 includes a high-performance silicon
bipolar RF power transistor and a thermally matched
biasing diode that matches the power transistor’s ther-
mal and process characteristics. This diode is used to
create a bias network that accurately controls the
power transistor’s collector current as the temperature
changes (Figure 2).
The biasing diode is a scaled version of the power tran-
sistor’s base-emitter junction, in such a way that the
current through the biasing diode is 1/15 the quiescent
collector current of the RF power transistor. Supplying
the biasing diode with a constant current source and
connecting the diode’s anode to the RF power transis-
tor’s base ensures that the RF power transistor’s quies-
cent collector current remains constant through
4
Figure 2. Bias Diode Application
temperature variations. Simply tying the biasing diode
to the supply through a resistor is adequate in most sit-
uations. If large supply variations are anticipated, con-
nect the biasing diode to a reference voltage through a
resistor, or use a stable current source. Connect the
biasing diode to the base of the RF power transistor
through a large RF impedance, such as an RF choke
(inductor), and decouple to ground through a surface-
mount chip capacitor larger than 1000pF.
_______________________________________________________________________________________
3.6V, 1W RF Power Transistors
for 900MHz Applications
Applications Information
Optimum Port Impedance
The source and load impedances presented to the
MAX2601/MAX2602 have a direct impact upon its gain,
output power, and linearity. Proper source- and load-
terminating impedances (Z
S
and Z
L
) presented to the
power transistor base and collector will ensure optimum
performance.
For a power transistor, simply applying the conjugate of
the transistor’s input and output impedances calculated
from small-signal S-parameters will yield less than opti-
mum device performance.
For maximum efficiency at V
BB
= 0.75V and V
CC
=
3.6V, the optimum power-transistor source and load
impedances (as defined in Figure 3) are:
At 836MHz: Z
S
= 5.5 + j2.0
Z
L
= 6.5 + j1.5
At 433MHz: Z
S
= 9.5 - j2.5
Z
L
= 8.5 - j1.5
Z
S
and Z
L
reflect the impedances that should be pre-
sented to the transistor’s base and collector. The pack-
age parasitics are dominated by inductance (as shown
in Figure 3), and need to be accounted for when calcu-
lating Z
S
and Z
L
.
The internal bond and package inductances shown
in Figure 3 should be included as part of the end-
application matching network, depending upon exact
layout topology.
Slug Layout Techniques
The most important connection to make to the
MAX2601/MAX2602 is the back side. It should connect
directly to the PC board ground plane if it is on the top
side, or through numerous plated through-holes if the
ground plane is buried. For maximum gain, this con-
nection should have very little self-inductance. Since it
is also the thermal path for heat dissipation, it must
have low thermal impedance, and the ground plane
should be large.
MAX2601/MAX2602
4
3
2
1
2.8nH
MAX2601
MAX2602
2.8nH
2.8nH
Z
S
Z
L
2.8nH
5
6
7
8
Figure 3. Optimum Port Impedance
Package Information
For the latest package outline information and land patterns, go
to
www.maxim-ic.com/packages.
PACKAGE TYPE
8 SOIC
PACKAGE CODE
S8E-12
DOCUMENT NO.
21-0041
_______________________________________________________________________________________
5
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