General Description
The MAX9981 dual high-linearity mixer integrates a local
oscillator (LO) switch, LO buffer, LO splitter, and two
active mixers. On-chip baluns allow for single-ended RF
and LO inputs. The active mixers eliminate the need for
an additional IF amplifier because the mixer provides a
typical overall conversion gain of 2.1dB.
The MAX9981 active mixers are optimized to meet the
demanding requirements of GSM850, GSM900, and
CDMA850 base-station receivers. These mixers provide
exceptional linearity with an input IP3 of greater than
+27dBm. The integrated LO driver allows for a wide
range of LO drive levels from -5dBm to +5dBm. In addi-
tion, the built-in high-isolation switch enables rapid LO
selection of less than 250ns, as needed for GSM trans-
ceiver designs.
The MAX9981 is available in a 36-pin QFN package
(6mm ✕6mm) with an exposed paddle, and is specified
over the -40°C to +85°C extended temperature range.
Applications
GSM850/GSM900 2G and 2.5G EDGE Base-
Station Receivers
Cellular cdmaOne™ and cdma2000™ Base-
Station Receivers
TDMA and Integrated Digital Enhanced Network
(iDEN)™ Base-Station Receivers
Digital and Spread-Spectrum Communication
Systems
Microwave Point-to-Point Links
Features
♦+27.3dBm Input IP3
♦+13.6dBm Input 1dB Compression Point
♦825MHz to 915MHz RF Frequency Range
♦70MHz to 170MHz IF Frequency Range
♦725MHz to 1085MHz LO Frequency Range
♦2.1dB Conversion Gain
♦10.8dB Noise Figure
♦42dB Channel-to-Channel Isolation
♦-5dBm to +5dBm LO Drive
♦+5V Single-Supply Operation
♦Built-In LO Switch with 52dB LO1 to LO2 Isolation
♦ESD Protection
♦Integrated RF and LO Baluns for Single-Ended
Inputs
MAX9981
825MHz to 915MHz, Dual SiGe High-Linearity
Active Mixer
________________________________________________________________ Maxim Integrated Products 1
Ordering Information
19-2588; Rev 0; 9/02
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.
PART TEMP RANGE PIN-PACKAGE
MAX9981EGX-T -40°C to +85°C 36 QFN-EP* (6mm × 6mm)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18 28
29
30
31
32
33
34
35
36
19
20
21
22
23
24
25
26
27 LO2
GND
GND
GND
MAINBIAS
DIVBIAS
TAPDIV
TAPMAIN
RFMAIN
RFDIV
GND
GND
GND
GND
GND
VCC
VCC
GND
GND
VCC
GND
GND
GND
IFDIV+
IFDIV-
VCC
IFMAIN+
IFMAIN-
LO1
LOSEL
GND
GND
GND
GND
GND
VCC
MAX9981
6mm x 6mm QFN-EP
TOP VIEW
Pin Configuration/
Functional Diagram
*EP = Exposed paddle.
cdmaOne is a trademark of CDMA Development Group.
cdma2000 is a trademark of Telecommunications Industry
Association.
iDEN is a trademark of Motorola, Inc.
MAX9981
825MHz to 915MHz, Dual SiGe High-Linearity
Active Mixer
2 _______________________________________________________________________________________
ABSOLUTE MAXIMUM RATINGS
DC ELECTRICAL CHARACTERISTICS
(Typical Application Circuit, VCC = +4.75V to +5.25V, no RF signals applied, all RF inputs and outputs terminated with 50Ω,
267Ωresistors connected from MAINBIAS and DIVBIAS to GND, TA= -40°C to +85°C, unless otherwise noted. Typical values are at
VCC = +5.0V, TA= +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.
VCC ........................................................................-0.3V to +5.5V
IFMAIN+, IFMAIN-, IFDIV+, IFDIV-,
MAINBIAS, DIVBIAS, LOSEL..................-0.3V to (VCC + 0.3V)
TAPMAIN, TAPDIV ..............................................................+5.5V
MAINBIAS, DIVBIAS Current ................................................5mA
RFMAIN, RFDIV, LO1, LO2 Input Power ........................+20dBm
Continuous Power Dissipation (TA= +70°C)
36-Pin QFN (derate 33mW/°C above +70°C)..............2200mW
Operating Temperature Range ...........................-40°C to +85°C
Junction Temperature......................................................+150°C
Storage Temperature Range .............................-65°C to +150°C
Lead Temperature (soldering, 10s) .................................+300°C
PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS
Supply Voltage VCC 4.75 5.00 5.25 V
Supply Current ICC 260 291 325 mA
Input High Voltage VIH 3.5 V
Input Low Voltage VIL 0.4 V
LOSEL Input Current ILOSEL -5 +5 µA
AC ELECTRICAL CHARACTERISTICS
(Typical Application Circuit, VCC = +4.75V to +5.25V, PLO = -5dBm to +5dBm, fRF = 825MHz to 915MHz, fLO = 725MHz to 1085MHz,
TA= -40°C to +85°C, unless otherwise noted. Typical values are at VCC = +5.0V, PRF = -5dBm, PLO = 0dBm, fRF = 870MHz,
fLO = 770MHz, TA= +25°C, unless otherwise noted.) (Notes 1, 2)
PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS
RF Frequency fRF 825 915 MHz
LO Frequency fLO 725 1085 MHz
IF Frequency fIF
Must meet RF and LO frequency range. IF
matching components affect IF frequency
range.
70 170 MHz
LO Drive Level PLO -5 +5 dBm
Cellular band,
fRF = 825MHz to
850MHz
2.7
Conversion Gain (Note 3) GC
VCC = +5.0V,
fIF = 100MHz,
low-side injection,
PRF = 0dBm,
PLO = -5dBm
GSM band,
fRF = 880MHz
to 915MHz
2.1
dB
Gain Variation from Nominal fRF = 825MHz to 915MHz, 3σ±0.6 dB
Conversion Loss from LO to IF
Inject PIN = -20dBm at fLO + 100MHz into
LO port. Measure 100MHz at IF port as
POUT. No RF signal at RF port.
53 dB
Cellular band,
fRF = 825MHz to 850MHz 10.8
Noise Figure NF
100MHz IF,
low-side
injection GSM band,
fRF = 880MHz to 915MHz 11.9
dB
MAX9981
825MHz to 915MHz, Dual SiGe High-Linearity
Active Mixer
_______________________________________________________________________________________ 3
Note 1: Guaranteed by design and characterization.
Note 2: All limits reflect losses of external components. Output measurements taken at IF OUT of Typical Application Circuit.
Note 3: Production tested.
Note 4: Two tones at 1MHz spacing, -5dBm per tone at RF port.
Note 5: Measured at IF port at IF frequency. fLO1 and fLO2 are offset by 1MHz.
Note 6: IF return loss can be optimized by external matching components.
AC ELECTRICAL CHARACTERISTICS (continued)
(Typical Application Circuit, VCC = +4.75V to +5.25V, PLO = -5dBm to +5dBm, fRF = 825MHz to 915MHz, fLO = 725MHz to 1085MHz,
TA= -40°C to +85°C, unless otherwise noted. Typical values are at VCC = +5.0V, PRF = -5dBm, PLO = 0dBm, fRF = 870MHz,
fLO = 770MHz, TA= +25°C, unless otherwise noted.) (Notes 1, 2)
PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS
Input 1dB Compression Point P1dB Low-side injection 13.6 dBm
Input Third-Order Intercept Point IIP3 PLO = -5dBm to +5dBm (Notes 3, 4) 27.3 dBm
Main 53.3
2 RF - 2 LO Spur Rejection 2 × 2 fRF = 915MHz, fLO = 815MHz,
fSPUR = 865MHz, PRF = -5dBm Diversity 43.2 dBc
3 RF - 3 LO Spur Rejection 3 × 3 fRF = 915MHz, fLO = 815MHz,
fSPUR = 848.3MHz, PRF = -5dBm 79.7 dBc
Maximum LO Leakage at RF Port PLO = -5dBm to +5dBm,
fLO = 725MHz to 1100MHz -42 dBm
Maximum LO Leakage at IF Port PLO = -5dBm to +5dBm,
fLO = 725MHz to 1100MHz -30.6 dBm
Minimum RF to IF Isolation PLO = -5dBm to +5dBm,
fRF = 825MHz to 915MHz 18 dB
LO1 to LO2 Isolation fRF = 825MHz to 915MHz, PLO1 = PLO2 =
+5dBm, fIF = 100MHz (Note 5) 52 dB
PRFMAIN = -5dBm, RFDIV
terminated with 50Ω.
Measured power at IFDIV
relative to IFMAIN.
39.5
Minimum Channel Isolation
fRF = 825MHz
to 915MHz,
fLO = 725MHz
to 1085MHz PRFDIV = -5dBm, RFMAIN
terminated with 50Ω.
Measured power at
IFMAIN relative to IFDIV.
42
dBc
LO Switching Time 50% of LOSEL to IF settled within 2°250 ns
RF Return Loss 25 dB
LO port selected 19
LO Return Loss LO port unselected 14.3 dB
IF Return Loss RF and LO terminated into 50Ω,
fIF = 100MHz (Note 6) 15 dB
MAX9981
825MHz to 915MHz, Dual SiGe High-Linearity
Active Mixer
4 _______________________________________________________________________________________
Typical Operating Characteristics
(Typical Application Circuit, VCC = 5.0V, PRF = -5dBm, PLO = 0dBm, TA= +25°C, unless otherwise noted.)
CONVERSION GAIN
vs. RF FREQUENCY LOW-SIDE INJECTION
MAX9981 toc01
RF FREQUENCY (MHz)
CONVERSION GAIN (dB)
900880860840
1
2
3
4
5
0
820 920
fIF = 100MHz
MAIN MIXER
TA = -40°C
TA = +85°C
TA = +25°C
CONVERSION GAIN
vs. RF FREQUENCY LOW-SIDE INJECTION
MAX9981 toc02
RF FREQUENCY (MHz)
CONVERSION GAIN (dB)
900880860840
1
2
3
4
5
0
820 920
fIF = 100MHz
MAIN MIXER
PLO = -5dBm, 0dBm, +5dBm
CONVERSION GAIN
vs. RF FREQUENCY LOW-SIDE INJECTION
MAX9981 toc03
RF FREQUENCY (MHz)
CONVERSION GAIN (dB)
900880860840
1
2
3
4
5
0
820 920
fIF = 100MHz
MAIN MIXER
VCC = 4.75V, 5.0V, 5.25V
CONVERSION GAIN
vs. RF FREQUENCY HIGH-SIDE INJECTION
MAX9981 toc04
RF FREQUENCY (MHz)
CONVERSION GAIN (dB)
900880860840
1
2
3
4
5
0
820 920
fIF = 120MHz
MAIN MIXER
TA = -40°C
TA = +85°CTA = +25°C
CONVERSION GAIN
vs. RF FREQUENCY HIGH-SIDE INJECTION
MAX9981 toc05
RF FREQUENCY (MHz)
CONVERSION GAIN (dB)
900880860840
1
2
3
4
5
0
820 920
fIF = 120MHz
MAIN MIXER
PLO = -5dBm, 0dBm, +5dBm
CONVERSION GAIN
vs. RF FREQUENCY HIGH-SIDE INJECTION
MAX9981 toc06
RF FREQUENCY (MHz)
CONVERSION GAIN (dB)
900880860840
1
2
3
4
5
0
820 920
fIF = 120MHz
MAIN MIXER
VCC = 4.75V, 5.0V, 5.25V
2 RF - 2 LO RESPONSE
vs. RF FREQUENCY LOW-SIDE INJECTION
MAX9981 toc07
RF FREQUENCY (MHz)
2 RF - 2 LO RESPONSE (dBc)
900880860840
50
55
60
65
70
75
80
45
820 920
fIF = 100MHz
MAIN MIXER
PRF = -5dBm
TA = +85°C
TA = +25°C
TA = -40°C
2 RF - 2 LO RESPONSE
vs. RF FREQUENCY LOW-SIDE INJECTION
MAX9981 toc08
RF FREQUENCY (MHz)
2 RF - 2 LO RESPONSE (dBc)
900880860840
55
65
75
85
45
820 920
PLO = -5dBm
PLO = 0dBm
PLO = +5dBm
fIF = 100MHz
MAIN MIXER
PRF = -5dBm
2 RF - 2 LO RESPONSE
vs. RF FREQUENCY LOW-SIDE INJECTION
MAX9981 toc09
RF FREQUENCY (MHz)
2 RF - 2 LO RESPONSE (dBc)
900880860840
50
55
60
65
70
75
80
45
820 920
fIF = 100MHz
MAIN MIXER
PRF = -5dBm
V
CC
= 4.75V, 5.0V, 5.25V
MAX9981
825MHz to 915MHz, Dual SiGe High-Linearity
Active Mixer
_______________________________________________________________________________________ 5
2 RF - 2 LO RESPONSE
vs. RF FREQUENCY LOW-SIDE INJECTION
MAX9981 toc10
RF FREQUENCY (MHz)
2 RF - 2 LO RESPONSE (dBc)
900880860840
45
50
55
60
40
820 920
fIF = 100MHz
DIVERSITY MIXER
PRF = -5dBm
TA = +85°C
TA = +25°C
TA = -40°C
2 RF - 2 LO RESPONSE
vs. RF FREQUENCY LOW-SIDE INJECTION
MAX9981 toc11
RF FREQUENCY (MHz)
2 RF - 2 LO RESPONSE (dBc)
900880860840
45
50
55
60
40
820 920
fIF = 100MHz
DIVERSITY MIXER
PRF = -5dBm
PLO = +5dBm
PLO = 0dBm
PLO = -5dBm
2 RF - 2 LO RESPONSE
vs. RF FREQUENCY LOW-SIDE INJECTION
MAX9981 toc12
RF FREQUENCY (MHz)
2 RF - 2 LO RESPONSE (dBc)
900880860840
45
50
55
60
40
820 920
fIF = 100MHz
DIVERSITY MIXER
PRF = -5dBm
V
CC
= 4.75V, 5.0V, 5.25V
2 LO - 2 RF RESPONSE
vs. RF FREQUENCY HIGH-SIDE INJECTION
MAX9981 toc13
RF FREQUENCY (MHz)
2 LO - 2 RF RESPONSE (dBc)
900880860840
50
55
65
60
70
45
820 920
fIF = 120MHz
MAIN MIXER
PRF = -5dBm
TA = +85°C
TA = +25°C
TA = -40°C
2 LO - 2 RF RESPONSE
vs. RF FREQUENCY HIGH-SIDE INJECTION
MAX9981 toc14
RF FREQUENCY (MHz)
2 LO - 2 RF RESPONSE (dBc)
900880860840
52
54
58
56
60
50
820 920
fIF = 120MHz
MAIN MIXER
PRF = -5dBm
PLO = -5dBm
PLO = +5dBm
PLO = 0dBm
2 LO - 2 RF RESPONSE
vs. RF FREQUENCY HIGH-SIDE INJECTION
MAX9981 toc15
RF FREQUENCY (MHz)
2 LO - 2 RF RESPONSE (dBc)
900880860840
52
54
58
56
60
50
820 920
fIF = 120MHz
MAIN MIXER
PRF = -5dBm
VCC = 5.25V
VCC = 4.75, 5.0V
2 LO - 2 RF RESPONSE
vs. RF FREQUENCY HIGH-SIDE INJECTION
MAX9981 toc16
RF FREQUENCY (MHz)
2 LO - 2 RF RESPONSE (dBc)
900880860840
41
42
43
46
45
44
47
40
820 920
fIF = 120MHz
DIVERSITY MIXER
PRF = -5dBm
TA = +85°C
TA = +25°C
TA = -40°C
2 LO - 2 RF RESPONSE
vs. RF FREQUENCY HIGH-SIDE INJECTION
MAX9981 toc17
RF FREQUENCY (MHz)
2 LO - 2 RF RESPONSE (dBc)
900880860840
40.0
42.5
45.0
50.0
47.5
52.5
37.5
820 920
fIF = 120MHz
DIVERSITY MIXER
PRF = -5dBm
PLO = +5dBm
PLO = -5dBm
PLO = 0dBm
2 LO - 2 RF RESPONSE
vs. RF FREQUENCY HIGH-SIDE INJECTION
MAX9981 toc18
RF FREQUENCY (MHz)
2 LO - 2 RF RESPONSE (dBc)
900880860840
43
44
45
46
42
820 920
fIF = 120MHz
DIVERSITY MIXER
PRF = -5dBm
VCC = 5.25V
VCC = 4.75V, 5.0V
Typical Operating Characteristics (continued)
(Typical Application Circuit, VCC = 5.0V, PRF = -5dBm, PLO = 0dBm, TA= +25°C, unless otherwise noted.)
MAX9981
825MHz to 915MHz, Dual SiGe High-Linearity
Active Mixer
6 _______________________________________________________________________________________
INPUT IP3
vs. RF FREQUENCY LOW-SIDE INJECTION
MAX9981 toc19
RF FREQUENCY (MHz)
INPUT IP3 (dBm)
900880860840
26
27
28
29
30
25
820 920
fIF = 100MHz
MAIN MIXER
TA = +85°C
TA = -40°C
TA = +25°C
INPUT IP3
vs. RF FREQUENCY LOW-SIDE INJECTION
MAX9981 toc20
RF FREQUENCY (MHz)
INPUT IP3 (dBm)
900880860840
26
27
28
29
30
25
820 920
fIF = 100MHz
MAIN MIXER
PLO = +5dBm
PLO = 0dBm
PLO = -5dBm
INPUT IP3
vs. RF FREQUENCY LOW-SIDE INJECTION
MAX9981 toc21
RF FREQUENCY (MHz)
INPUT IP3 (dBm)
900880860840
26
27
28
29
30
25
820 920
fIF = 100MHz
MAIN MIXER
VCC = 5.25V
VCC = 4.75V
VCC = 5.0V
INPUT IP3
vs. RF FREQUENCY HIGH-SIDE INJECTION
MAX9981 toc22
RF FREQUENCY (MHz)
INPUT IP3 (dBm)
900880860840
26
27
28
29
30
25
820 920
fIF = 120MHz
MAIN MIXER
TA = +85°C
TA = -40°C
TA = +25°C
INPUT IP3
vs. RF FREQUENCY HIGH-SIDE INJECTION
MAX9981 toc23
RF FREQUENCY (MHz)
INPUT IP3 (dBm)
900880860840
26
27
28
29
30
25
820 920
fIF = 120MHz
MAIN MIXER
PLO = +5dBm
PLO = 0dBm
PLO = -5dBm
INPUT IP3
vs. RF FREQUENCY HIGH-SIDE INJECTION
MAX9981 toc24
RF FREQUENCY (MHz)
INPUT IP3 (dBm)
900880860840
26
27
28
29
30
25
820 920
fIF = 120MHz
MAIN MIXER
VCC = 5.25V
VCC = 4.75V
VCC = 5.0V
INPUT P1dB
vs. RF FREQUENCY LOW-SIDE INJECTION
MAX9981 toc25
RF FREQUENCY (MHz)
INPUT P1dB (dBm)
900880860840
13
14
15
16
17
12
820 920
fIF = 100MHz
MAIN MIXER
TA = +85°C
TA = -40°C
TA = +25°C
INPUT P1dB
vs. RF FREQUENCY LOW-SIDE INJECTION
MAX9981 toc26
RF FREQUENCY (MHz)
INPUT P1dB (dBm)
900880860840
13
14
15
16
17
12
820 920
fIF = 100MHz
MAIN MIXER
PLO = +5dBm
PLO = 0dBm
PLO = -5dBm
INPUT P1dB
vs. RF FREQUENCY LOW-SIDE INJECTION
MAX9981 toc27
RF FREQUENCY (MHz)
INPUT P1dB (dBm)
900880860840
13
14
15
16
17
12
820 920
fIF = 100MHz
MAIN MIXER
VCC = 5.25V
VCC = 4.75V
VCC = 5.0V
Typical Operating Characteristics (continued)
(Typical Application Circuit, VCC = 5.0V, PRF = -5dBm, PLO = 0dBm, TA= +25°C, unless otherwise noted.)
MAX9981
825MHz to 915MHz, Dual SiGe High-Linearity
Active Mixer
_______________________________________________________________________________________ 7
INPUT P1dB
vs. RF FREQUENCY HIGH-SIDE INJECTION
MAX9981 toc28
RF FREQUENCY (MHz)
INPUT P1dB (dBm)
900880860840
13
14
15
16
17
12
820 920
fIF = 120MHz
MAIN MIXER
TA = +85°C
TA = -40°C
TA = +25°C
INPUT P1dB
vs. RF FREQUENCY HIGH-SIDE INJECTION
MAX9981 toc29
RF FREQUENCY (MHz)
INPUT P1dB (dBm)
900880860840
13
14
15
16
17
12
820 920
fIF = 120MHz
MAIN MIXER
PLO = +5dBm
PLO = 0dBm
PLO = -5dBm
INPUT P1dB
vs. RF FREQUENCY HIGH-SIDE INJECTION
MAX9981 toc30
RF FREQUENCY (MHz)
INPUT P1dB (dBm)
900880860840
13
14
15
16
17
12
820 920
fIF = 120MHz
MAIN MIXER
VCC = 5.25V
VCC = 4.75V
VCC = 5.0V
CHANNEL ISOLATION
vs. RF FREQUENCY LOW-SIDE INJECTION
MAX9981 toc31
RF FREQUENCY (MHz)
CHANNEL ISOLATION (dBc)
900880860840
40
45
50
55
35
820 920
RF MAIN IN/IF DIVERSITY OUT
fIF = 100MHz
TA = +85°C
TA = +25°C
TA = -40°C
CHANNEL ISOLATION
vs. RF FREQUENCY LOW-SIDE INJECTION
MAX9981 toc32
RF FREQUENCY (MHz)
CHANNEL ISOLATION (dBc)
900880860840
40
45
50
55
35
820 920
RF MAIN IN/IF DIVERSITY OUT
fIF = 100MHz
PLO = -5dBm, 0dBm, +5dBm
CHANNEL ISOLATION
vs. RF FREQUENCY LOW-SIDE INJECTION
MAX9981 toc33
RF FREQUENCY (MHz)
CHANNEL ISOLATION (dBc)
900880860840
40
45
50
55
35
820 920
RF DIVERSITY IN/IF MAIN OUT
fIF = 100MHz
PLO = -5dBm, 0dBm, +5dBm
CHANNEL ISOLATION
vs. RF FREQUENCY HIGH-SIDE INJECTION
MAX9981 toc34
RF FREQUENCY (MHz)
CHANNEL ISOLATION (dBc)
900880860840
40
45
50
55
35
820 920
RF MAIN IN/IF DIVERSITY OUT
fIF = 120MHz
TA = +85°C
TA = +25°C
TA = -40°C
CHANNEL ISOLATION
vs. RF FREQUENCY HIGH-SIDE INJECTION
MAX9981 toc35
RF FREQUENCY (MHz)
CHANNEL ISOLATION (dBc)
900880860840
40
45
50
55
35
820 920
RF MAIN IN/IF DIVERSITY OUT
fIF = 120MHz
PLO = -5dBm, 0dBm, +5dBm
CHANNEL ISOLATION
vs. RF FREQUENCY HIGH-SIDE INJECTION
MAX9981 toc36
RF FREQUENCY (MHz)
CHANNEL ISOLATION (dBc)
900880860840
40
45
50
55
35
820 920
RF DIVERSITY IN/IF MAIN OUT
fIF = 120MHz
PLO = -5dBm, 0dBm, +5dBm
Typical Operating Characteristics (continued)
(Typical Application Circuit, VCC = 5.0V, PRF = -5dBm, PLO = 0dBm, TA= +25°C, unless otherwise noted.)
MAX9981
825MHz to 915MHz, Dual SiGe High-Linearity
Active Mixer
8 _______________________________________________________________________________________
LO SWITCH ISOLATION
vs. RF FREQUENCY LOW-SIDE INJECTION
MAX9981 toc37
RF FREQUENCY (MHz)
LO SWITCH ISOLATION (dBc)
900880860840
52
53
54
55
56
51
820 920
LO OFFSET 1MHz
fIF = 100MHz
DIVERSITY MIXER
TA = +85°C
TA = +25°C
TA = +-40°C
LO SWITCH ISOLATION
vs. RF FREQUENCY LOW-SIDE INJECTION
MAX9981 toc38
RF FREQUENCY (MHz)
LO SWITCH ISOLATION (dBc)
900880860840
52
53
54
55
56
51
820 920
LO OFFSET 1MHz
fIF = 100MHz
DIVERSITY MIXER PLO = -5dBm
PLO = 0dBm
PLO = +5dBm
LO SWITCH ISOLATION
vs. RF FREQUENCY HIGH-SIDE INJECTION
MAX9981 toc39
RF FREQUENCY (MHz)
LO SWITCH ISOLATION (dBc)
900880860840
52
53
54
55
56
51
820 920
LO OFFSET 1MHz
fIF = 120MHz
MAIN MIXER
TA = +85°C
TA = +25°CTA = -40°C
LO LEAKAGE AT IF PORT
vs. LO FREQUENCY
MAX9981 toc40
LO FREQUENCY (MHz)
LO LEAKAGE (dBm)
950900850800
-42
-39
-36
-33
-30
-45
750 1000
TA = +85°C
TA = +25°C
TA = -40°C
MAIN MIXER
LO LEAKAGE AT IF PORT
vs. LO FREQUENCY
MAX9981 toc41
LO FREQUENCY (MHz)
LO LEAKAGE (dBm)
950900850800
-42
-39
-36
-33
-30
-27
750 1000
MAIN MIXER
PLO = +5dBm
PLO = -5dBm
PLO = 0dBm
LO LEAKAGE AT RF PORT
vs. LO FREQUENCY
MAX9981 toc42
LO FREQUENCY (MHz)
LO LEAKAGE (dBm)
1000900800
-70
-65
-60
-55
-50
-45
-40
700 1100
MAIN MIXER
PLO = +5dBm
PLO = -5dBm
PLO = 0dBm
RF TO IF ISOLATION
vs. RF FREQUENCY
MAX9981 toc43
RF FREQUENCY (MHz)
RF TO IF ISOLATION (dB)
900880860840
18
21
24
27
30
15
820 920
TA = +85°C
TA = +25°C
TA = -40°C
MAIN MIXER
RF TO IF ISOLATION
vs. RF FREQUENCY
MAX9981 toc44
RF FREQUENCY (MHz)
RF TO IF ISOLATION (dB)
900880860840
20
22
24
26
18
820 920
MAIN MIXER
PLO = -5dBm
PLO = 0dBm, +5dBm
NOISE FIGURE
vs. RF FREQUENCY LOW-SIDE INJECTION
MAX9981 toc45
RF FREQUENCY (MHz)
NOISE FIGURE (dB)
900880860840
9
11
10
12
13
14
15
8
820 920
TA = -40°C
TA = +25°C
TA = +85°C
fIF = 100MHz
MAIN MIXER
Typical Operating Characteristics (continued)
(Typical Application Circuit, VCC = 5.0V, PRF = -5dBm, PLO = 0dBm, TA= +25°C, unless otherwise noted.)
MAX9981
825MHz to 915MHz, Dual SiGe High-Linearity
Active Mixer
_______________________________________________________________________________________ 9
RF RETURN LOSS vs. RF FREQUENCY
MAX9981 toc46
RF FREQUENCY (MHz)
RF RETURN LOSS (dB)
1000900800
30
25
20
15
10
5
0
35
700 1100
MAIN MIXER
PLO = -5dBm, 0dBm, +5dBm
IF RETURN LOSS vs. IF FREQUENCY
MAX9981 toc47
IF FREQUENCY (MHz)
IF RETURN LOSS (dB)
17515012575 100
15
10
5
0
20
50 200
MAIN MIXER
SET BY EXTERNAL MATCHING
LO RETURN LOSS vs. LO FREQUENCY
MAX9981 toc48
LO FREQUENCY (MHz)
LO RETURN LOSS (dB)
1000900800
35
25
30
20
15
10
5
0
700 1100
PLO = +5dBm
PLO = -5dBm
PLO = 0dBm
LO INPUT SELECTED
LO RETURN LOSS vs. LO FREQUENCY
MAX9981 toc49
LO FREQUENCY (MHz)
LO RETURN LOSS (dB)
1000900800
35
25
30
20
15
10
5
0
700 1100
LO INPUT UNSELECTED
PLO = -5dBm, 0dBm, +5dBm
SUPPLY CURRENT vs. TEMPERATURE
MAX9981 toc50
TEMPERATURE (°C)
SUPPLY CURRENT (mA)
603510-15
270
280
290
300
310
320
260
-40 85
VCC = 5.25V
VCC = 5.0V
VCC = 4.75V
Typical Operating Characteristics (continued)
(Typical Application Circuit, VCC = 5.0V, PRF = -5dBm, PLO = 0dBm, TA= +25°C, unless otherwise noted.)
MAX9981
825MHz to 915MHz, Dual SiGe High-Linearity
Active Mixer
10 ______________________________________________________________________________________
Pin Description
PIN NAME FUNCTION
1 RFMAIN Main Channel RF Input. This input is internally matched to 50Ω and is DC shorted to ground
through a balun.
2 TAPMAIN Main RF Balun Center Tap. Connect bypass capacitors from this pin to ground.
3 MAINBIAS Bias control for the Main Mixer. Connect a 267Ω resistor from this pin to ground to set the bias
current for the main mixer.
4, 5, 6, 11,
12, 15, 17,
18, 20, 22,
24, 25, 26,
28, 29, 31,
34, 35, EP
GND Ground
7 DIVBIAS Bias Control for the Diversity Mixer. Connect a 267Ω resistor from this pin to ground to set the bias
current for the diversity mixer.
8 TAPDIV Diversity RF Balun Center Tap. Connect bypass capacitors from this pin to ground.
9 RFDIV Diversity Channel RF Input. This input is internally matched to 50Ω and is DC shorted to ground
through a balun.
10, 16, 21,
30, 36 VCC Power-Supply Connections. Connect bypass capacitors as shown in the Typical Application
Circuit.
13, 14 IFDIV+, IFDIV- Differential IF Output for Diversity Mixer. Connect 560nH pullup inductors and 137Ω pullup
resistors from each of these pins to VCC for a 70MHz to 100MHz IF range.
19 LO1 Local Oscillator Input 1. This input is internally matched to 50Ω and is DC shorted to ground
through a balun.
23 LOSEL Local Oscillator Select. Set this pin to logic HIGH to select LO1; set to logic LOW to select LO2.
27 LO2 Local Oscillator Input 2. This input is internally matched to 50Ω and is DC shorted to ground
through a balun.
32, 33 IFMAIN-,
IFMAIN+
Differential IF Output for the Main Mixer. Connect 560nH pullup inductors and 137Ω pullup
resistors from each of these pins to VCC for a 70MHz to 100MHz IF range.
MAX9981
825MHz to 915MHz, Dual SiGe High-Linearity
Active Mixer
______________________________________________________________________________________ 11
Typical Application Circuit
RF_MAIN
RF_DIV
R1
R2
C2C11
C12 C3
C1
C4
C6
C9
C17
L3
L4 R6
R5
C20
C18
C19
IFDIV_OUT
T2
C10
C5
5.0V
C13
L2
L1 R3
R4
C16
C15
C14
IFMAIN_OUT
T1
C8
LO2
C7
LO1
4:1 (200:50)
TRANSFORMER
4:1 (200:50)
TRANSFORMER
3
2
14
6
3
2
14
6
5.0V
5.0V
5.0V
5.0V
5.0V
5.0V
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18 28
29
30
31
32
33
34
35
36
19
20
21
22
23
24
25
26
27 LO2
GND
GND
GND
MAINBIAS
DIVBIAS
TAPDIV
TAPMAIN
RFMAIN
RFDIV
GND
GND
GND
GND
GND
V
CC
V
CC
GND
GND
V
CC
GND
GND
GND
IFDIV+
IFDIV-
V
CC
IFMAIN+
IFMAIN-
LO1
LOSEL
GND
GND
GND
GND
GND
VCC
MAX9981
LO SELECT
MAX9981
Detailed Description
The MAX9981 downconverter mixers are designed for
GSM and CDMA base-station receivers with an RF fre-
quency between 825MHz and 915MHz. Each active
mixer provides 2.1dB to 2.7dB of overall conversion
gain to the receive signal, removing the need for an
external IF amplifier. The mixers have excellent input
IP3 measuring greater than +27dBm. The device also
features integrated RF and LO baluns that allow the
mixers to be driven with single-ended signals.
RF Inputs
The MAX9981 has two RF inputs (RFMAIN, RFDIV) that are
internally matched to 50Ωrequiring no external matching
components. A 33pF DC-blocking capacitor is required at
the input since the input is internally DC shorted to ground
through a balun. Return loss is better than 15dB over the
entire frequency range of 825MHz to 915MHz.
LO Inputs
The mixers can be used for either high-side or low-side
injection applications with an LO frequency range of
725MHz to 1085MHz. An internal LO switch allows for
switching between two single-ended LO ports. This is
useful for fast frequency changes/frequency hopping. LO
switching time is less than 250ns. The switch is controlled
by a digital input (LOSEL) that when high, selects LO1
and when low, selects LO2. The selected LO input mixes
with both RFMAIN and RFDIV to produce the IF signals.
Internal LO buffers allow for a wide power range on the
LO ports. The LO signal power can vary from -5dBm to
+5dBm. LO1 and LO2 are internally matched to 50Ω, so
only a 15pF DC-blocking capacitor is required at each
LO port.
IF Outputs
Each mixer has an IF frequency range of 70MHz to
170MHz. The differential IF output ports require exter-
nal pullup inductors to VCC to resonate out the differen-
tial on-chip capacitance of 1.8pF. See the Typical
Application Circuit for recommended component val-
ues for an IF of 70MHz to 100MHz. The IF match can
be optimized for higher IF frequencies by reducing the
values of the pullup inductors L1, L2, L3, and L4. Note:
Removing the ground plane from underneath these
inductors reduces parasitic capacitive loading and
improves VSWR.
Bias Circuitry
Connect bias resistors from MAINBIAS and DIVBIAS to
ground to set the mixer bias current. A nominal resistor
value of 267Ωsets an input IP3 of +27dBm and supply
current of 290mA. Bias currents are fine-tuned at the
factory and should not be adjusted.
Applications Information
Layout Considerations
A properly designed PC board is an essential part of
any RF/microwave circuit. Keep RF signal lines as short
as possible to reduce losses, radiation, and induc-
tance. For best performance, route the ground pin
traces directly to the exposed paddle underneath the
package. This paddle should be connected to the
ground plane of the board by using multiple vias under
the device to provide the best RF/thermal conduction
path. Solder the exposed paddle, on the bottom of the
device package, to a PC board exposed pad.
825MHz to 915MHz, Dual SiGe High-Linearity
Active Mixer
12 ______________________________________________________________________________________
Component List
COMPONENT VALUE SIZE PART NUMBER
C1, C4 33pF 0603 Murata GRM1885C1H330J
C2, C3 3.9pF 0603 Murata GRM1885C1H3R9C
C5, C6, C9, C10 100pF 0603 Murata GRM1885C1H101J
C7, C8 15pF 0603 Murata GRM1885C1H150J
C11, C12 0.033µF 0603 Murata GRM188R71E333K
C13, C16, C17, C20 220pF 0603 Murata GRM1885C1H221J
C14, C15, C18, C19 330pF 0603 Murata GRM1885C1H331J
L1–L4 560nH 1008 CoilCraft 1008CS-561XJBB
R1, R2 267Ω ±1% 0603 —
R3–R6 137Ω ±1% 0603 —
T1, T2 4:1 (200:50) —Mini-Circuits TC4-1W-7A
Power Supply Bypassing
Proper voltage supply bypassing is essential for high-fre-
quency circuit stability. Bypass each VCC pin, TAPMAIN,
and TAPDIV with the capacitors shown in the typical
application circuit. Place the TAPMAIN and TAPDIV
bypass capacitors to ground within 100mils of the
TAPMAIN and TAPDIV pins.
Chip Information
TRANSISTOR COUNT: 358
PROCESS: BiCMOS
MAX9981
825MHz to 915MHz, Dual SiGe High-Linearity
Active Mixer
______________________________________________________________________________________ 13
MAX9981
825MHz to 915MHz, Dual SiGe High-Linearity
Active Mixer
14 ______________________________________________________________________________________
Package Information
(The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information,
go to www.maxim-ic.com/packages.)
36L,40L, QFN.EPS
MAX9981
825MHz to 915MHz, Dual SiGe High-Linearity
Active Mixer
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.
Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 ____________________ 15
© 2002 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products.
Package Information (continued)
(The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information,
go to www.maxim-ic.com/packages.)
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