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MAX2602 Evaluation Kit
_______________General Description
The MAX2602 evaluation kit (EV kit) simplifies the evalu-
ation of the MAX2602 1W RF power transistor for
900MHz band applications. The EV kit demonstrates
the MAX2602 in a 3.6V, 836MHz, 1W (30dBm) RF
power amplifier for constant-envelope applications.
The EV kit is shipped with a MAX2602, which contains
an internal biasing diode. With a simple modification,
the MAX2602 EV kit can be used to emulate the
MAX2601, which does not have an internal biasing
diode.
____________________________Features
o
1W (30dBm) Output Power at 836MHz
o
50Ω Inputs and Outputs
o
+2.7V to +5.5V Supply Range
o
11dB Gain at 836MHz
Evaluates: MAX2601/MAX2602
______________Ordering Information
PART
MAX2602EVKIT-SO
TEMP. RANGE
-40°C to +85°C
BOARD TYPE
Surface Mount
____________________Component List
DESIGNATION QTY
C1, C2
C3
C4
C5–C8,
C11, C12
C9, C11
L1
L2
R1
R2
R3
IN, OUT
U1
None
None
2
1
1
6
2
1
1
1
1
1
2
1
1
1
DESCRIPTION
2pF surface-mount capacitors
10pF surface-mount capacitor
12pF surface-mount capacitor
1000pF surface-mount capacitors
0.1µF surface-mount capacitors
100nH surface-mount inductor
18.5nH surface-mount spring inductor
Coilcraft A05T (Note 1)
430Ω surface-mount resistor
24Ω surface-mount resistor
0Ω resistor
Edge-mount SMA connectors
MAX2602ESA (8-pin, thermally
enhanced SO)
MAX2601/MAX2602 data sheet
Printed circuit board
_________________________Quick Start
The following section provides instructions for setting
up the MAX2602 EV kit as a 1W RF power amplifier.
Test Equipment Required
•
•
•
•
RF signal generator capable of at least 20dBm of
output power at 836MHz
Attenuator that can handle at least 30dBm (1W) of
RF power (used to protect the test equipment)
RF spectrum analyzer for use at 836MHz (alterna-
tively, a power meter can be used)
DC power supply capable of delivering 1A at +2.7V
to +5.5V
Connections and Setup
Follow these steps for connecting the EV kit:
1) Connect a 50Ω RF signal generator capable of sup-
plying at least 20dBm at 836MHz to the RF input
SMA connector (“IN”). Set the generator’s initial out-
put to a much lower power (-10dBm, for instance).
Keep this generator’s RF output off at this time.
2) Connect a fixed attenuator that can handle 1W of
power to the output SMA connector (“OUT”). This
attenuator reduces the power to the test equipment
and protects it from overload. Connect this attenua-
tor’s output to a spectrum analyzer that is set to dis-
play 836MHz. It may be possible to set a reference-
level offset on the analyzer to compensate for the
attenuator. Consult your spectrum analyzer’s manu-
al for details.
3) Set the power supply to +3.6V with a 1A current
limit. Disable the output. Connect the power supply
to the V
C
terminal on the EV kit through an ammeter.
Note 1: Contact Coilcraft by phone at (800) 322-2645, by fax at
(847) 639-1469, or on the World Wide Web at
http://www.coilcraft.com.
________________________________________________________________
Maxim Integrated Products
1
For free samples & the latest literature: http://www.maxim-ic.com, or phone 1-800-998-8800.
For small orders, phone 408-737-7600 ext. 3468.
MAX2602 Evaluation Kit
Evaluates: MAX2601/MAX2602
4) Connect the same power supply through a separate
lead to the EV kit’s V
B
terminal.
5) Verify that all the connections are correct to avoid
damaging the transistor or your test equipment.
6) Turn on the 3.6V supply. Note the supply current
with the RF generator off. It should be around
100mA.
7) Activate the RF signal generator and slowly
increase the generator’s output power to 20dBm. At
this time, the supply current should be about
500mA, and the output power should be 30dBm.
emitter inductance as low as possible, as excessive
emitter inductance can degrade the performance of
any RF common-emitter amplifier. The bottom-side con-
tact is also the principal path for heat dissipation, and
must be connected to a large ground plane.
Biasing
Capacitors C5, C9, and C11 provide decoupling for the
bias supply. The transistor’s bias current is set by the
internal biasing diode’s current. This current is set by
the following equation:
I
B
=
V
B
- 0.75V
R1
_______________Detailed Description
Figure 1 is the schematic for the MAX2602 EV kit as
shipped. The circuit consists of four blocks: power-sup-
ply decoupling, a bias network, and both input and out-
put matching networks. The amplifier built on this board
is biased for class AB operation at 1W of output power,
and provides high efficiency.
The collector current is scaled to the bias current:
I
C
= 15I
B
. R3 is used as a jumper. The transistor’s base
is biased through R2 and L1 (a choke). For more infor-
mation on the internal biasing diode’s operation, refer to
the MAX2601/MAX2602 data sheet.
Supply Decoupling Circuitry
and Grounding
Capacitors C8 and C10 provide decoupling for V
C
. The
collector has two separate pins: one for the V
C
input (con-
nected through choke L2), and one for the RF output.
The most important contact for the MAX2602 is not on
the top of the board; it is the bottom-side emitter con-
tact that is connected to ground. This contact keeps
Input Matching Network
The transistor’s RF input does not present a 50Ω
impedance, so a matching network is required for prop-
er operation in a 50Ω environment. This network con-
sists of capacitor C1 to ground, approximately 1 inch
(or 2.5cm) of the 50Ω transmission line (T1), a DC-
blocking capacitor (C6), and a shunt capacitor at the
transistor base (C4).
V
B
C9
0.1µF
C5
1000pF
R1
430Ω
C11
1000pF
R3
0Ω
C12
1000pF
C8
1000pF
C7
1000pF
C10
0.1µF
V
C
L1
100nH
C6
1000pF
R2
24Ω
L2
18.5nH
3
1
4
8
OUT
C3
10pF
T2
C2
2pF
IN
C1
2pF
T1
C4
12pF
U1
5
2, 6, 7
BACK-SIDE SLUG
Figure 1. MAX2602 EV Kit Schematic
2
_______________________________________________________________________________________
MAX2602 Evaluation Kit
Evaluates: MAX2601/MAX2602
V
B
C9
0.1µF
C5
1000pF
R1
0Ω
C11
1000pF
C12
1000pF
C8
1000pF
C7
1000pF
C10
0.1µF
V
C
L1
100nH
C6
1000pF
L2
18.5nH
R2
24Ω
4
5
3
1
8
OUT
C3
10pF
T2
C2
2pF
IN
C1
2pF
T1
C4
12pF
U1
2, 6, 7
BACK-SIDE SLUG
Figure 2. MAX2602 EV Kit Schematic Without the Bias Diode
Output Matching Network
The RF output is taken from pin 8 and is not at 50Ω
impedance, so a matching network is required. The
matching network consists of a shunt capacitor at the
collector (C3), a DC-blocking capacitor (C7), a 50Ω
transmission line (T2), and a shunt capacitor (C2).
this mode, be sure to turn the V
C
supply on before the
V
B
supply. When turning the part off, turn the V
B
supply
off first and then the V
C
supply. External bias voltages
ranging from 0V to 0.85V are typically used.
_____________Layout Considerations
For best results, use the MAX2602 EV kit as a layout
guide. The most critical connection is the emitter-
ground contact on the MAX2602’s bottom side. On the
EV kit, this contact is made through a large (0.1 inch,
2.5mm diameter) plated through-hole in the board,
located directly under the part. This contact must be
soldered directly to a large ground plane, as it is the
principal path for heat dissipation, as well as the low-
inductance emitter ground. The MAX2602 EV kit uses
its ground plane as the heatsink.
Evaluating the MAX2602
Without the Biasing Diode
To evaluate the MAX2602 without the biasing diode
(functionally equivalent to the MAX2601), the 0Ω resis-
tor (R3) must be removed, and the 430Ω resistor (R1)
must be replaced by a 0Ω resistor (a short) (Figure 2).
Now an external bias voltage may be connected to the
EV kit’s V
B
input. The biasing diode is no longer con-
nected, so the EV kit will not work without an external
biasing voltage. To avoid damage to the MAX2602 in
_______________________________________________________________________________________
3
MAX2602 Evaluation Kit
Evaluates: MAX2601/MAX2602
1.0"
Figure 3. MAX2602 EV Kit Component Placement Guide
1.0"
Figure 4. MAX2602 EV Kit PC Board Layout—Component Side
1.0"
Figure 5. MAX2602 EV Kit PC Board Layout—Solder Side (ground
plane and heatsink)
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.
4
_____________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600
© 1997 Maxim Integrated Products
Printed USA
is a registered trademark of Maxim Integrated Products.

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