19-1449; Rev 1; 6/05
Direct-Conversion Tuner IC
General Description
The MAX2108 is a low-cost direct-conversion tuner IC
designed for use in digital direct-broadcast satellite
(DBS) television set-top box units and microwave links.
Its direct-conversion architecture reduces system cost
compared to devices with IF-based architectures.
The MAX2108 directly tunes L-band signals to base-
band using a broadband I/Q downconverter. The oper-
ating frequency range spans from 950MHz to
2150MHz. The IC includes a low-noise amplifier (LNA)
with gain control, two downconverter mixers with output
buffers, a 90° quadrature generator, and a divide-by
32/33 prescaler.
o
Low-Cost Architecture
o
Operates from Single +5V Supply
o
On-Chip Quadrature Generator, Dual-Modulus
Prescaler (/32, /33)
o
Input Levels: -20dBm to -70dBm per Carrier
o
Over 50dB RF Gain-Control Range
o
10dB Noise Figure at Maximum Gain
o
+8dBm IIP3 at Minimum Gain
Features
MAX2108
Applications
DirecTV, PrimeStar, EchoStar DBS Tuners
DVB-Compliant DBS Tuners
Cellular Base Stations
Wireless Local Loop
Broadband Systems
LMDS
Microwave Links
PART
MAX2108CEG
MAX2108CEG+
Ordering Information
TEMP RANGE
0°C to +70°C
0°C to +70°C
PIN-PACKAGE
24 QSOP
24 QSOP
+Denotes
lead-free package.
Pin Configuration appears at end of data sheet.
Functional Diagram
V
CC
12
PS_SEL
11
GC
10
GND
9
GND
8
RFIN
7
RFIN
6
V
CC
5
GND
4
V
CC
3
IOUT
2
IOUT
1
I
/32
/33
0
90
MAX2108
Q
13
PSOUT
14
PSOUT
15
GND
16
GND
17
N.C.
18
LO
19
LO
20
N.C.
21
V
CC
22
GND
23
QOUT
24
QOUT
________________________________________________________________
Maxim Integrated Products
1
For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct! at
1-888-629-4642, or visit Maxim’s website at www.maxim-ic.com.
Direct-Conversion Tuner IC
MAX2108
ABSOLUTE MAXIMUM RATINGS
V
CC
to GND ..............................................................-0.3V to +7V
V
CC
to Any Other V
CC
...........................................-0.3V to +0.3V
All Other Pins to GND.................................-0.3V to (V
CC
+ 0.3V)
RFIN to
RFIN
..........................................................................±2V
LO to
LO
................................................................................±2V
Short-Circuit Current
IOUT,
IOUT,
QOUT,
QOUT
to GND .................................10mA
PSOUT,
PSOUT
to GND...................................................40mA
Short-Circuit Duration IOUT to
IOUT,
QOUT to
QOUT,
PSOUT to
PSOUT
............................................................10sec
Continuous Power Dissipation (T
A
= +70°C)
24 QSOP (derate 10mW/°C above T
A
= +70°C) ..........800mW
Operating Temperature Range...............................0°C to +70°C
Junction Temperature ......................................................+150°C
Storage Temperature Range .............................-65°C to +150°C
Lead Temperature (soldering, 10s) .................................+300°C
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.
DC ELECTRICAL CHARACTERISTICS
(V
CC
= +4.75V to +5.25V; V
GC
= 1.3V; PS_SEL = 0.5V; IOUT,
IOUT,
QOUT,
QOUT
= terminated with 2.5kΩ to GND; no input signal
applied; T
A
= 0°C to +70°C; unless otherwise noted. Typical values are at V
CC
= +5V, T
A
= +25°C.)
PARAMETER
Supply Current
PS_SEL Logic-High Threshold
PS_SEL Logic-Low Threshold
PS_SEL Input Bias Current
GC Input Bias Current
IOUT,
IOUT,
QOUT,
QOUT
Common-Mode Output Voltage
SYMBOL
I
CC
V
THH
V
THL
I
PS_SEL
I
GC
V
CM
0 < V
PS_SEL
< V
CC
1V < V
GC
< 4V
-30
-80
2.9
3.35
2.4
0.5
+10
+80
3.8
CONDITIONS
MIN
TYP
105
MAX
152
UNITS
mA
V
V
µA
µA
V
AC ELECTRICAL CHARACTERISTICS
(V
CC
= +5V; PS_SEL = 0.5V; P
RFIN
= -20dBm; f
LO
= f
RFIN
+125kHz; GC set via servo loop for V
IOUT
- V
IOUT
= 200mVp-p (differen-
tial); T
A
= +25°C; unless otherwise noted.)
PARAMETER
RFIN Frequency Range (Note 1)
RFIN Maximum Input Power
(Note 2)
RFIN Minimum Input Power
(Note 2)
External LO Drive Level (Note 2)
Gain-Control Range (Note 2)
RFIN Input Third-Order
Intercept Point (Note 3)
RFIN Input Second-Order
Intercept Point (Note 4)
Noise Figure
IIP
3
IIP
2
NF
V
GC
= 4V, f
LO
= 1750MHz
1V < V
GC
< 4V, P
LO
= -5dBm
50
8
14
10
SYMBOL
f
RFIN
P
RFINMAX
950MHz < f
RFIN
< 2150MHz, P
LO
= -5dBm
P
RFINMIN
950MHz < f
RFIN
< 2150MHz, P
LO
= -5dBm,
V
IOUT
- V
IOUT
= 10mV
P-P
, T
A
= 0°C +70°C
-5
CONDITIONS
MIN
950
-20
-70
TYP
MAX
2150
UNITS
MHz
dBm
dBm
dBm
dB
dBm
dBm
dB
2
_______________________________________________________________________________________
Direct-Conversion Tuner IC
AC ELECTRICAL CHARACTERISTICS (continued)
(V
CC
= +5V; PS_SEL = 0.5V; P
RFIN
= -20dBm; f
LO
= f
RFIN
+125kHz; GC set via servo loop for V
IOUT
- V
IOUT
= 200mVp-p (differen-
tial); T
A
= +25°C; unless otherwise noted.)
PARAMETER
Prescaler Divide Ratio
Differential Prescaler Output
Swing
I/Q Channel Quadrature
Phase Error (Note 2)
I/Q Amplitude Mismatch
(Note 2)
I/Q Channel Clipping Level
Baseband Bandwidth
I/Q Channel Differential
Output Impedance
V
PSOUT -
V
PSOUT
SYMBOL
V
PS_SEL
> 2.4V
V
PS_SEL
< 0.5V
C
PSOUT
= C
PSOUT
= 10pF to GND
f
IOUT
= f
IOUT
= f
QOUT
= f
QOUT
= 125kHz
f
IOUT
= f
IOUT
= f
QOUT
= f
QOUT
= 125kHz
f
IOUT
= f
IOUT
= f
QOUT
= f
QOUT
= 10MHz,
no output load
At -3dB attenuation
f
IOUT
= f
IOUT
= f
QOUT
= f
QOUT
= 20MHz
1.4
150
33
CONDITIONS
MIN
32
33
1.0
3
1
TYP
MAX
32
33
V
P-P
degrees
dB
V
P-P
MHz
Ω
UNITS
MAX2108
Note 1:
AC specifications with minimum/maximum limits are met within this frequency range.
Note 2:
LO and
LO
are differentially driven through an AC-coupled matching network.
Note 3:
P
RFIN
= -20dBm per tone, GC set via servo loop for V
IOUT
- V
IOUT
= 20mVp-p per tone. f1
RFIN
= 1749MHz, f2
RFIN
=
1751MHz, f
LO
= 1740MHz.
Note 4:
P
RFIN
= -20dBm per tone, GC set via servo loop for V
IOUT
- V
IOUT
= 20mVp-p per tone. f1
RFIN
= 1200MHz, f2
RFIN
=
2150MHz, f
LO
= 951MHz.
Typical Operating Characteristics
(T
A
= +25°C, unless otherwise noted.)
SUPPLY CURRENT
vs. SUPPLY VOLTAGE
MAX2108 toc01
CARRIER LEVEL vs. GAIN CONTROL
MAX2108 toc02
INPUT IP3 vs. FREQUENCY
MAX2108 toc03
125
120
115
I
CC
(mA)
110
105
T
A
= +25°C
100
95
90
4.75
4.85
4.95
5.05
5.15
T
A
= 0°C
T
A
= +70°C
0
-10
-20
RF LEVEL (dBm)
f
RFIN
= 1750 MHz
-40
-50
-60
-70
-80
GC SET FOR 10mV
P-P
BASEBAND OUTPUT
10
8
IIP3 (dBm)
-30
6
4
TWO-TONE FREQUENCY
SPACING EQUALS 2MHz
2
0
1
1.5
2
2.5
3
3.5
900
1100
1300
1500
1700
GC VOLTAGE (V)
RF FREQUENCY (MHz)
5.25
V
CC
(V)
_______________________________________________________________________________________
3
Direct-Conversion Tuner IC
MAX2108
Typical Operating Characteristics (continued)
(T
A
= +25°C, unless otherwise noted.)
IM3 vs. CARRIER LEVEL
MAX2108 toc04
NOISE FIGURE vs. FREQUENCY
MAX2108 toc05
NOISE FIGURE vs. INSERTION GAIN
(RF TO BASEBAND)
MAX2108 toc06
80
70
60
IM3 (dBc)
15
14
13
12
NF (dB)
25
20
NF (dB)
V
GC
= 4V
5
950
1150
1350
1550
1750
20
22
24
26
28
30
32
34
36
38
RF FREQUENCY (MHz)
GAIN (dB)
40
30
20
SERIES IMPEDANCE (Ω)
10
0
-10
-20
-30
-40
-50
-60
-70
900
1100
1300
1500
1700
FREQUENCY (MHz)
IMAGINARY
REAL
50
40
30
20
10
0
-55 -50 -45 -40 -35 -30 -25 -20 -15 -10
RF INPUT LEVEL (dBm)
TWO-TONE FREQUENCY
SPACING EQUALS 2MHz
11
10
9
8
7
6
5
15
10
RF PORT SERIES IMPEDANCE
vs. FREQUENCY
30
SERIES IMPEDANCE (Ω)
20
10
0
-10
-20
-30
-40
900
1100
1300
1500
1700
FREQUENCY (MHz)
V
GC
= 4V
1900
2100
IMAGINARY
REAL
MAX2108 toc07
RF PORT SERIES IMPEDANCE
vs. FREQUENCY
MAX2108 toc08
40
V
GC
= 1V
1900
2100
LO PORT SERIES IMPEDANCE
vs. FREQUENCY
MAX2108 toc10
10
SERIES IMPEDANCE (Ω)
0
-10
-20
-30
-40
-50
-60
-70
900
1100
1300
1500
SINGLE-ENDED
1700
1900
2100
IMAGINARY
NORMALIZED BASEBAND GAIN (dB)
20
REAL
0
-5
0.1
1
10
100
1000
BASEBAND FREQUENCY (MHz)
FREQUENCY (MHz)
4
_______________________________________________________________________________________
MAX2108 toc11
30
5
NORMALIZED BASEBAND GAIN
vs. BASEBAND FREQUENCY
Direct-Conversion Tuner IC
Pin Description
PIN
1
2
3
4
5
6
7
8, 9
10
11
12
13
14
15
16
17, 20
18
19
21
22
23
24
NAME
IOUT
IOUT
V
CC
GND
V
CC
RFIN
RFIN
GND
GC
PS_SEL
V
CC
PSOUT
PSOUT
GND
GND
N.C.
LO
LO
V
CC
GND
QOUT
QOUT
Inverting I-Channel Baseband Output
Noninverting I-Channel Baseband Output
Downconverter +5V Supply. Bypass with a 10pF capacitor to GND as close to the IC as possible. Connect
an additional 0.1µF capacitor in parallel with the 10pF capacitor.
Ground. Connect to a low-inductance ground plane.
RF +5V Supply. Bypass with a 22pF capacitor to GND as close to the IC as possible.
Inverting RF Input. Connect to a 22pF capacitor in series with a 75Ω resistor to GND.
Noninverting RF Input. Connect via matching network to a 75Ω cable.
RF Ground. Connect to a low-inductance ground plane.
Gain-Control Input. Apply a voltage between 1V and 4V to control the gain of the RF amplifier. Bypass with a
1000pF capacitor to minimize noise on the control line.
Prescaler Modulus Control. Drive PS_SEL <0.5V to operate in divide-by-33 mode. Drive PS_SEL >2.4V to
operate in divide-by-32 mode.
Prescaler +5V Supply. Bypass with a 1000pF capacitor to GND.
Inverting Prescaler Output
Noninverting Prescaler Output
Prescaler Ground. Connect to a low-inductance ground plane.
Local Oscillator Ground. Connect to a low-inductance ground plane.
No Connection. Do not make any connection to this pin.
Inverting LO Input
Noninverting LO Input
Local Oscillator +5V Supply. Bypass with a 22pF capacitor and a 0.1µF capacitor to pin 16.
Downconverter Ground. Connect to a low-inductance ground plane.
Noninverting Q-Channel Baseband Output
Inverting Q-Channel Baseband Output
FUNCTION
MAX2108
_______________________________________________________________________________________
5
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