Manual
MAX2685
Low-Cost, 900MHz, Low-Noise Amplifier
and Downconverter Mixer
4 _______________________________________________________________________________________
Typical Operating Characteristics (continued)
(MAX2685 EV kit, V
CC
= V
SHDN
= +3V, f
LNAIN
= f
MIXIN
= 880MHz, f
LO
= 960MHz, P
LNAIN
= -30dBm, P
LO
= -8dBm, P
MIXIN
= -25dBm,
differential IFOUT operation, Z
o
= 50Ω, T
A
= +25°C, unless otherwise noted.)
-10
0
-5
10
5
15
20
2.5 3.5 4.03.0 4.5 5.0 5.5
LNA INPUT IP3 vs. SUPPLY VOLTAGE
MAX2685 toc04
SUPPLY VOLTAGE (V)
INPUT IP3 (dBm)
GAIN = HIGH
GAIN = LOW
T
A
= +85°C
T
A
= +25°C
T
A
= -40°C
T
A
= +85°C
T
A
= +25°C
T
A
= -40°C
-20
-10
-15
0
-5
5
10
15
20
800 850 875825 900 925 950 975 1000
LNA GAIN vs. FREQUENCY
MAX2685 toc05
FREQUENCY (MHz)
GAIN (dB)
GAIN = HIGH
GAIN = LOW
1.0
1.2
1.1
1.4
1.3
1.6
1.5
1.7
1.9
1.8
2.0
870 890 900 910880 920 930 940 950 960
LNA NOISE FIGURE vs. FREQUENCY
MAX2685 toc06
FREQUENCY (MHz)
NOISE FIGURE (dB)
-40
-30
-35
-20
-25
-15
-10
-5
0
800 850 875825 900 925 950 975 1000
LNA REVERSE ISOLATION vs. FREQUENCY
MAX2685 toc07
FREQUENCY (MHz)
REVERSE ISOLATION (dB)
GAIN = HIGH
GAIN = LOW
LNA S11 vs. FREQUENCY
(800MHz to 1000MHz UNMATCHED)
MAX2685 toc10
GAIN = HIGH
GAIN = LOW
800
1000
800
HI
LO
1000
-15
-12
-13
-14
-11
-10
-9
-8
-7
-6
-5
800 880840 920 960 1000
LNA INPUT RETURN LOSS vs. FREQUENCY
MAX2685 toc08
FREQUENCY (MHz)
INPUT RETURN LOSS (dB)
GAIN = HIGH
GAIN = LOW
-20
-14
-16
-18
-12
-10
-8
-6
-4
-2
0
800 880840 920 960 1000
LNA OUTPUT RETURN LOSS vs. FREQUENCY
MAX2685 toc09
FREQUENCY (MHz)
OUTPUT RETURN LOSS (dB)
GAIN = HIGH
GAIN = LOW
3.0
3.5
4.0
4.5
5.0
5.5
6.0
6.5
7.0
2.5 3.53.0 4.0 4.5 5.0 5.5
MIXER GAIN vs. SUPPLY VOLTAGE
MAX2685 toc11
SUPPLY VOLTAGE (V)
GAIN (dB)
T
A
= -40°C
T
A
= +85°C
T
A
= +85°C
T
A
= +25°C
T
A
= +25°C
T
A
= -40°C
GAIN = HIGH
GAIN = LOW
-10
-4
-6
-8
-2
0
2
4
6
8
10
2.5 3.53.0 4.0 4.5 5.0 5.5
MIXER INPUT IP3 vs. SUPPLY VOLTAGE
MAX2685 toc12
SUPPLY VOLTAGE (V)
INPUT IP3 (dBm)
GAIN = HIGH
GAIN = LOW
T
A
= +85°C
T
A
= +25°C
T
A
= -40°C
T
A
= +85°C
T
A
= +25°C
T
A
= -40°C