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MAX2601ESA+

P1-P3P4-P6
MAX2601/MAX2602
3.6V, 1W RF Power Transistors
for 900MHz Applications
4 _______________________________________________________________________________________
_______________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.
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
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.
V
BB
V
CC
5Ω
RF
IN
T1
T2
L1
0.1μF
2pF
L1
=
T1, T2 =
COILCRAFT A05T INDUCTOR, 18.5nH
1", 50Ω TRANSMISSION LINE ON FR-4
1000pF
0.1μF1000pF
1000pF
1000pF
100nH
24Ω
12pF
10pF
1
8
2, 6, 7
BACKSIDE
SLUG
4
5
2pF
Figure 1. Test Circuit
C
BIAS
RF
IN
RF
OUT
C
IN
C
OUT
V
CC
V
CC
Q2
RF
C
R
BIAS
RF
C
Q1
Figure 2. Bias Diode Application
MAX2601/MAX2602
3.6V, 1W RF Power Transistors
for 900MHz Applications
_______________________________________________________________________________________ 5
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.
Z
S
Z
L
2.8nH
2.8nH
2.8nH
2.8nH
1234
8765
MAX2601
MAX2602
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 PACKAGE CODE DOCUMENT NO.
8 SOIC S8E-12
21-0041
MAX2601/MAX2602
3.6V, 1W RF Power Transistors
for 900MHz Applications
Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are
implied. Maxim reserves the right to change the circuitry and specifications without notice at any time.
6
_____________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600
© 2008 Maxim Integrated Products Maxim is a registered trademark of Maxim Integrated Products, Inc.
Revision History
REVISION
NUMBER
REVISION
DATE
DESCRIPTION
PAGES
CHANGED
2 5/97 — —
3 9/08 Removed die version from Ordering Information 1
P1-P3P4-P6

MAX2601ESA+

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Description:
RF Bipolar Transistors 3.6V 1W RF Pwr Trans for 900MHz Ap
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