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MAX2235EUP+

P1-P3P4-P6P7-P8
MAX2235
+3.6V, 1W Autoramping Power
Amplifier for 900MHz Applications
4 _______________________________________________________________________________________
Typical Operating Characteristics
(MAX2235 Evaluation Kit, GC = unconnected, f
RFIN
= 836MHz, V
CC
= V
SHDN
= +3.6V, T
A
= +25°C, unless otherwise noted.)
0
200
100
400
300
600
500
700
010155 20253035
SUPPLY CURRENT vs. OUTPUT POWER
MAX2235 toc01
OUTPUT POWER (dBm)
I
CC
(mA)
T
A
= -40°C
T
A
= +25°C
T
A
= +85°C
-20
0
-10
20
10
30
40
0 1.00.5 1.5 2.0 2.5
OUTPUT POWER
vs. VOLTAGE AT GC PIN
MAX2235 toc02
V
GC
(V)
OUTPUT POWER (dBm)
P
RFIN
= 0dBm
T
A
= -40°C
T
A
= +25°C
T
A
= +85°C
0
10
5
20
15
30
25
35
-25 -15 -10-20 -5 0 5 10
OUTPUT POWER vs. INPUT POWER
MAX2235 toc03
INPUT POWER (dBm)
OUTPUT POWER (dBm)
V
CC
= +5.0V
V
CC
= +3.6V
V
CC
= +3.0V
V
CC
= +2.7V
0
10
5
20
15
30
25
35
-25 -15 -10-20 -5 0 5 10
OUTPUT POWER vs. INPUT POWER
AND TEMPERATURE
MAX2235 toc04
INPUT POWER (dBm)
OUTPUT POWER (dBm)
T
A
= -40°C
T
A
= +25°C
T
A
= +85°C
0
20
10
40
30
50
60
015205 10 253035
EFFICIENCY vs. OUTPUT POWER
MAX2235 toc07
OUTPUT POWER (dBm)
EFFICIENCY (%)
V
CC
= +5.0V
V
CC
= +3.6V
V
CC
= +3.0V
V
CC
= +2.7V
-60
-40
-50
-20
-30
-10
0
-25 -10 -5-20 -15 0 5 10
SECOND AND THIRD HARMONICS
vs. INPUT POWER
MAX2235 toc05
INPUT POWER (dBm)
HARMONIC POWER (dBm)
2nd
3rd
0
10
5
20
15
30
25
35
820 830 835825 840 845 850 855
OUTPUT POWER vs. FREQUENCY
MAX2235 toc06
INPUT FREQUENCY (MHz)
OUTPUT POWER (dBm)
P
RFIN
= +3dBm
P
RFIN
= -5dBm
P
RFIN
= -13dBm
P
RFIN
= -21dBm
MATCHED AT
836MHz
0
10
5
20
15
30
25
35
010155 20253035
POWER GAIN vs. OUTPUT POWER
MAX2235 toc08
OUTPUT POWER (dBm)
POWER GAIN (dB)
V
CC
= +5.0V
V
CC
= +3.6V
V
CC
= +3.0V
40
V
CC
= +2.7V
0
10
5
20
15
35
30
25
40
0105 1520253035
POWER GAIN vs. OUTPUT POWER
AND TEMPERATURE
MAX2235 toc09
OUTPUT POWER (dBm)
POWER GAIN (dB)
T
A
= -40°C
T
A
= +25°C
T
A
= +85°C
MAX2235
+3.6V, 1W Autoramping Power
Amplifier for 900MHz Applications
_______________________________________________________________________________________ 5
0
400
200
800
600
1200
1000
1400
0406020 80 100 120
RISE TIME vs. RAMPING CAPACITANCE
MAX2235 toc10
CAPACITANCE (nF)
RISE TIME (µs)
FULL POWER = +20dBm
FULL POWER = +10dBm
FULL POWER = +30dBm
Typical Operating Characteristics (continued)
(MAX2235 Evaluation Kit, GC = unconnected, f
RFIN
= 836MHz, V
CC
= V
SHDN
= +3.6V, T
A
= +25°C, unless otherwise noted.)
0
400
200
800
600
1000
1200
0406020 80 100 120
FALL TIME vs. RAMPING CAPACITANCE
MAX2235 toc11
CAPACITANCE (nF)
FALL TIME (µs)
FULL POWER = +20dBm
FULL POWER = +10dBm
FULL POWER = +30dBm
NAME FUNCTION
1 RFIN
RF Input. A DC blocking capacitor in series with RFIN is required. The value of the capacitor depends on
the operating frequency.
PIN
Pin Description
2 GND
GND connection for the input stage (variable-gain amplifier). Connect to the circuit board ground plane
with a separate low-inductance path (via).
3 V
CC
Supply Voltage Input for the Input Stage. Bypass with its own 100pF low-inductance capacitor to GND.
4 V
CC
Supply Voltage Input for Bias Circuitry. Bypass with its own 100pF low-inductance capacitor and a 1000pF
capacitor to GND, to minimize RF signal coupling into the bias circuits.
5 V
CC
Supply Voltage Input for the Input Stage. Bypass with its own 22pF low-inductance capacitor to pins 6 and 7.
6, 7, 10 GND
GND Connection for the Second-Stage Amplifier (driver). Connect to the circuit board ground plane with a
separate low-inductance path (via).
8 V
CC
Supply Voltage Input for the Second Stage. Bypass with its own 220pF and 1000pF low-inductance
capacitors to GND.
9 V
CC
Supply Voltage Input for the Second Stage. Connect to pin 8.
11 RAMP
Power Ramp Pin. Connect a capacitor between RAMP and REF to provide a gradual linear power-up/down
ramp. See Detailed Description.
12 REF Reference Voltage for RAMP Capacitor. The reference is internally set to 1.9V.
13, 14,
17, 18,
SLUG
GND
GND Connection for the Power Stage. Solder the slug to the circuit board ground plane. Connect pins 13,
14, 17, and 18 to the slug with a straight board trace under the chip.
15 RFOUT
Power Amplifier Output. See Typical Operating Circuit for an example of a matching network, which pro-
vides optimal output power at 836MHz. Connect to pin 16.
16 RFOUT Power Amplifier Output. Connect to pin 15.
19
SHDN
Shutdown Pin. Drive SHDN low to turn the device off. Drive above 2.0V to turn the device on. Drive V
SHDN
> 2.0V and V
GC
< 0.4V for standby mode.
20 GC
Gain-Control Pin. Apply V
GC
between 0.6V and 2.3V to control the output power with a monotonic dB/V
relationship. See the Typical Operating Characteristics for a typical relationship.
MAX2235
+3.6V, 1W Autoramping Power
Amplifier for 900MHz Applications
6 _______________________________________________________________________________________
Detailed Description
The MAX2235 power amplifier (PA) operates over a
wide frequency range of 800MHz to 1000MHz. The sig-
nal path consists of three stages: the input stage, the
driver stage, and the power stage. There are matching
circuits between the first and second stages, and
between the second and third stages. The bias circuits
process external commands to control the device’s
power-up/down and the gain of the PA.
Input Stage
The first stage is a variable-gain amplifier with 37dB
gain-control range. The input transistor acts as a
transconductor with constant bias current. Gain control
is achieved by steering the signal current from the input
transistor to the first output matching network (to drive
the second stage) or to a separate supply pin. This
stage operates in class A and remains on in standby
mode to ensure that the VSWR at the input does not
vary more than 1.5:1 compared with normal operation.
The input stage typically requires an external inductor
to achieve an optimum input VSWR.
Second Stage (Driver)
The driver produces a signal large enough to drive the
power stage into saturation. The driver stage operates
in Class C and is off during standby.
Second- and Third-Stage Matching
The interstage matching networks provide optimal load-
ing and power transfer. The circuits are on-chip to save
board space. The bandwidths of the matching net-
works allow the PA to operate over a wide frequency
range.
Typical Operating Circuit
20
19
18
17
8
7
6
5
4
3
2
1
16
15
14
13
9
10
11
12
GND
V
CC
V
CC
V
CC
GND
GND
V
CC
V
CC
GND
RFIN
SHDN
GND
GND
RFOUT
RFOUT
GND
GND
REF
RAMP
GC
0.068µF
470pF
470pF
1500pF
47pF
1000pF
1000pF
11pF
MAX2235
68pF
V
CC
V
CC
V
CC
V
CC
V
CC
J2
JU2
JU1
SMA
SMA
J3
J4
8.2nH
*
100pF
100pF
1000pF
1000pF
22pF
100pF
100pF
0.01µF1µF
J1
1
2
3
* VALUE OF OUTPUT INDUCTOR DEPENDS ON APPLICATION.
P1-P3P4-P6P7-P8

MAX2235EUP+

Mfr. #:
Buy MAX2235EUP+
Manufacturer:
Maxim Integrated
Description:
RF Amplifier Autoramping Power Amp for 900MHz Ap
Lifecycle:
New from this manufacturer.
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