Maxim MAX2685EEE Datasheet
For free samples & the latest literature: http://www.maxim-ic.com, or phone 1-800-998-8800.
For small orders, phone 1-800-835-8769.
General Description
The MAX2685’s low-noise amplifier (LNA) and downconverter mixer comprise the major blocks of an RF
front-end receiver. Optimized for 900MHz operation,
the device’s low noise figure, high gain, and high linearity make it ideal for cellular, cordless, and wireless data
applications. A low supply current of 8.5mA (high-gain
mode) and 3.8mA (low-gain mode) plus a low operating
supply voltage range of +2.7V to +5.5V make it suitable
for use in 3-cell NiCd or 1-cell lithium-ion (Li+) battery
applications. A low-power shutdown mode further
extends battery life by reducing supply current below
0.1µA.
The MAX2685 includes an LNA, LNA bypass switch,
downconverter mixer, and local-oscillator (LO) buffer.
The LNA has a low noise figure of 1.4dB, a high gain of
15dB, and an input third-order intercept point (IP3) of
-4dBm. The mixer has a noise figure of 13dB, a gain of
6dB, and an input IP3 of +7dBm. In addition, an LNA
bypass switch allows two levels of gain, reducing
power consumption when high gain is not needed.
The downconverter mixer has a single-ended RF input
port and differential IF output ports. Differential operation of the IF ports offers improved even-order harmonic
rejection and increased immunity to noise. An LO buffer
allows the LO port to be driven with only -8dBm of LO
power. The MAX2685 is offered in a space-saving 16pin QSOP package.
Applications
Cellular/Cordless Phones 900MHz ISM-Band Radios
Wireless Data 868MHz European ISM Band
Features
♦ 800MHz to 1000MHz RF Frequency Range
♦ +2.7V to +5.5V Single-Supply Operation
♦ Integrated LNA + Mixer + LO Buffer
♦ Logic-Controlled LNA Bypass Switch Reduces
Supply Current
♦ LNA Performance (High/Low Gain)
Gain: +15dB/-12dB
NF: 1.4dB/12dB
Input IP3: -4dBm/+16dBm
♦ Mixer Performance (High/Low Gain)
Gain: 6dB/4.6dB
NF: 13dB/12dB
Input IP3: +7dBm/-1.5dBm
♦ Supply Current
8.5mA (High Gain)
3.8mA (Low Gain)
♦ <0.1µA Supply Current in Shutdown Mode
♦ 0.8µs Receiver Enable Time
MAX2685
Low-Cost, 900MHz, Low-Noise Amplifier
and Downconverter Mixer
________________________________________________________________
Maxim Integrated Products
1
V
CC
IFOUT+
IFOUT-
MAX2685
LNAIN
GAIN
LNA
LO
LNAOUT
MIXIN
LNA BYPASS
LO
BUFFER
MIXER
SHDN
POWER
MANAGEMENT
GND
16
15
14
13
12
11
10
9
1
2
3
4
5
6
7
8
LNAOUT
GND
V
CC
V
CC
MIXIN
GND
GND
IFOUT+
IFOUT-
TOP VIEW
MAX2685
QSOP
LNAIN
SHDN
GAIN
GND
GND
LO
GND
Functional Diagram
19-1493; Rev 0; 7/99
PART
MAX2685EEE -40°C to +85°C
TEMP. RANGE PIN-PACKAGE
16 QSOP
EVALUATION KIT MANUAL
FOLLOWS DATA SHEET
Pin Configuration
Ordering Information
MAX2685
Low-Cost, 900MHz, Low-Noise Amplifier
and Downconverter Mixer
2 _______________________________________________________________________________________
ABSOLUTE MAXIMUM RATINGS
DC ELECTRICAL CHARACTERISTICS
(VCC= +2.7V to +5.5V, V
SHDN
= +2V, V
GAIN
= +2V, LNAIN = LNAOUT = MIXIN = LO = unconnected, IFOUT+ = IFOUT- = VCC, T
A
= -40°C to +85°C. Typical values are at TA= +25°C and VCC= +3V, unless otherwise noted.)
AC ELECTRICAL CHARACTERISTICS
(MAX2685 EV kit, VCC= V
SHDN
= +3V, f
LNAIN
= f
MIXIN
= 880MHz, fLO= 960MHz, P
LNAIN
= -30dBm, PLO= -8dBm, P
MIXIN
= -25dBm,
differential IFOUT operation, Z
o
= 50Ω, T
A
= +25°C, unless otherwise noted.)
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.
VCCto GND..............................................................-0.3V to +6V
LNAIN Input Power (50Ω source)...................................+10dBm
LO Input Power (50Ω source) ........................................+10dBm
MIXIN Input Power (50Ω source) ...................................+10dBm
IFOUT+, IFOUT- to GND ..........................................-0.3V to +6V
LNAOUT to GND ......................................................-0.3V to +6V
GAIN, SHDN to GND..................................-0.3V to (V
CC
+ 0.3V)
Continuous Power Dissipation (T
A
= +70°C)
16-Pin QSOP (derate 8.3mW/°C above +70°C)............667mW
Junction Temperature......................................................+150°C
Operating Temperature Range ...........................-40°C to +85°C
Storage Temperature Range .............................-65°C to +150°C
Lead Temperature (soldering, 10sec) .............................+300°C
SHDN = GND
GAIN = V
CC
GAIN, SHDN
GAIN, SHDN
V
SHDN
= V
GAIN
= 0 to 5.5V
CONDITIONS
µA0.1 1.0Shutdown Supply Current
8.5 14.1
V2.7 5.5Supply Voltage Range
V2.0Logic Input Voltage High
V0.5Logic Input Voltage Low
µA±0.01 ±1Logic Input Current
UNITSMIN TYP MAXPARAMETER
GAIN = GND
mA
3.8 6.4
Operating Supply Current
GAIN = GND
dB
-14 -12 -10.3
GAIN = VCC, TA= T
MIN
to T
MAX
(Note 2)
LNA Gain
GAIN = V
CC
GAIN = V
CC
GAIN = GND
GAIN = V
CC
CONDITIONS
dB0.9 1.6LNA Gain Variation over Temperature
13 15 16.2
1.4
dB
12.2
LNA Noise Figure
-18.4LNA Input 1dB Compression
UNITSMIN TYP MAXPARAMETER
MHz800 1000RF Frequency Range (Note 1)
GAIN = V
CC
GAIN = GND
dBm
-18.6
dB
-11.3
LNAOUT Port Return Loss
MHz800 1000RF Frequency Range (Note 1)
GAIN = GND
dB
2.5 4.6 6.0
Mixer Conversion Gain
GAIN = V
CC
4.7 6.1 7.0
GAIN = V
CC
(Note 3)
GAIN = GND (Note 4)
-4.1
dBm
+16.2
LNA Input IP3
LOW-NOISE AMPLIFIER (LNA)
DOWNCONVERTER MIXER
MAX2685
Low-Cost, 900MHz, Low-Noise Amplifier
and Downconverter Mixer
_______________________________________________________________________________________ 3
AC ELECTRICAL CHARACTERISTICS (continued)
(MAX2685 EV kit, VCC= V
SHDN
= +3V, f
LNAIN
= f
MIXIN
= 880MHz, fLO= 960MHz, P
LNAIN
= -30dBm, PLO= -8dBm, P
MIXIN
= -25dBm,
differential IFOUT operation, Z
o
= 50Ω, T
A
= +25°C, unless otherwise noted.)
Note 1: This is the recommended operating frequency range.
Note 2: Maximum and minimum limits are guaranteed by design and device characterization and are not production tested.
Note 3: Two tones at 880MHz and 880.1MHz, -30dBm per tone.
Note 4: Two tones at 880MHz and 880.1MHz, -10dBm per tone.
Note 5: Two tones at 880MHz and 880.1MHz, -25dBm per tone.
Note 6: Time from SHDN = high, until the cascaded receive gain is within 1dB of its final value. Measured with 47pF blocking
capacitors on LNAIN and LNAOUT. Matching network removed from IFOUT output.
Typical Operating Characteristics
(MAX2685 EV kit, VCC= V
SHDN
= +3V, f
LNAIN
= f
MIXIN
= 880MHz, fLO= 960MHz, P
LNAIN
= -30dBm, PLO= -8dBm, P
MIXIN
= -25dBm,
differential IFOUT operation, Z
o
= 50Ω, T
A
= +25°C, unless otherwise noted.)
0
3
2
1
4
5
6
7
8
9
10
2.5 3.53.0 4.0 4.5 5.0 5.5
SUPPLY CURRENT vs. SUPPLY VOLTAGE
MAX2685 toc01
SUPPLY VOLTAGE (V)
SUPPLY CURRENT (mA)
GAIN = HIGH
GAIN = LOW
TA = +85°C
TA = +25°C
TA = -40°C
TA = +85°C
TA = +25°C
TA = -40°C
0
3
2
1
4
5
6
7
8
9
10
2.5 3.53.0 4.0 4.5 5.0 5.5
SHUTDOWN SUPPLY CURRENT
vs. SUPPLY VOLTAGE
MAX2685 toc02
SUPPLY VOLTAGE (V)
SHUTDOWN SUPPLY CURRENT (nA)
SHDN = GND
TA = -40°C
TA = +25°C
TA = +85°C
-15
-5
-10
5
0
15
10
20
2.5 3.5 4.03.0 4.5 5.0 5.5
LNA GAIN vs. SUPPLY VOLTAGE
MAX2685 toc03
SUPPLY VOLTAGE (V)
GAIN (dB)
GAIN = HIGH
GAIN = LOW
TA = +85°C
TA = +25°C
TA = -40°C
TA = +85°C
TA = +25°C
TA = -40°C
GAIN = GND
dB
12.1
Mixer Noise Figure (SSB)
GAIN = VCC, TA= T
MIN
to T
MAX
(Note 2)
GAIN = V
CC
dB12
Mixer Conversion Gain Variation over
Temperature
(Note 6)
dB
GAIN = V
CC
GAIN = GND
CONDITIONS
µs0.8Receiver Enable Time
13
7
dBm
-1.5
Mixer Input IP3 (Note 5)
11LO Port Return Loss
UNITSMIN TYP MAXPARAMETER
dB
SHDN = VCCor GND
53LO-to-LNAIN Isolation
dB
dB
28LNAOUT-to-MIXIN Isolation
31LO-to-MIXIN Isolation
OVERALL SYSTEM
Loading...