MAX9985ETX [MAXIM]
Dual, SiGe, High-Linearity, 700MHz to 1000MHz Downconversion Mixer with LO Buffer/Switch; 双通道，SiGe ，高线性度， 700MHz至1000MHz下变频混频器，带有LO缓冲器/开关
| 型号： | MAX9985ETX |
| 厂家： | 
MAXIM INTEGRATED PRODUCTS |
| 描述： | Dual, SiGe, High-Linearity, 700MHz to 1000MHz Downconversion Mixer with LO Buffer/Switch |
| 文件： | 总15页 (文件大小：217K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
19-0705 Rev 0; 1/07
Dual, SiGe, High-Linearity, 700MHz to 1000MHz
Downconversion Mixer with LO Buffer/Switch
MAX985
General Description
Features
The MAX9985 high-linearity, dual-channel downconver-
sion mixer is designed to provide approximately 6dB
gain, +28.5dBm of IIP3, and 10.5dB of noise figure (NF)
ideal for diversity receiver applications. With a 700MHz
to 1000MHz RF frequency range and a 570MHz to
865MHz LO frequency range, this mixer is ideal for low-
side LO injection architectures. In addition, the broad
frequency range makes the MAX9985 ideal for GSM
850/950, 2G/2.5G EDGE, WCDMA, cdma2000®, and
iDEN® base-station applications.
ꢀ 700MHz to 1000MHz RF Frequency Range
ꢀ 570MHz to 865MHz LO Frequency Range
ꢀ 50MHz to 250MHz IF Frequency Range
ꢀ 6dB Typical Conversion Gain
ꢀ 10.5dB Typical Noise Figure
ꢀ +28.5dBm Typical Input IP3
ꢀ +16.2dBm Typical Input 1dB Compression Point
ꢀ 77dBc Typical 2RF-2LO Spurious Rejection at
The MAX9985 dual-channel downconverter achieves a
high level of component integration. The MAX9985 inte-
grates two double-balanced active mixer cores, two LO
buffers, a dual-input LO selectable switch, and a pair of
differential IF output amplifiers. In addition, integrated
on-chip baluns at the RF and LO ports allow for single-
ended RF and single-ended LO inputs. The MAX9985
requires a typical 0dBm LO drive. Supply current is
adjustable up to 400mA.
P
RF
= -10dBm
ꢀ Dual Channels Ideal for Diversity Receiver
Applications
ꢀ 47dB Typical Channel-to-Channel Isolation
ꢀ -3dBm to +3dBm LO Drive
ꢀ Integrated LO Buffer
ꢀ Internal RF and LO Baluns for Single-Ended
The MAX9985 is available in a 36-pin thin QFN pack-
age (6mm x 6mm) with an exposed paddle. Electrical
performance is guaranteed over the extended tempera-
Inputs
ꢀ Built-In SPDT LO Switch with 43dB LO1-to-LO2
Isolation and 50ns Switching Time
ture range, from T = -40°C to +85°C.
C
ꢀ Pin-Compatible with MAX9995/MAX9995A
Applications
1700MHz to 2200MHz Mixers
850MHz WCDMA Base Stations
ꢀ Lead-Free Package Available
Ordering Information
PKG
GSM 850/GSM 950, 2G/2.5G EDGE Base
Stations
cdmaOne™ and cdma2000 Base Stations
iDEN Base Stations
PART
TEMP RANGE PIN-PACKAGE
CODE
36 Thin QFN-EP*
-40°C to +85°C
Fixed Broadband Wireless Access
Wireless Local Loop
MAX9985ETX
T3666-2
(6mm x 6mm)
36 Thin QFN-EP*
-40°C to +85°C (6mm x 6mm), T3666-2
T/R
Private Mobile Radios
MAX9985ETX-T
MAX9985ETX+
Military Systems
Digital and Spread-Spectrum Communication
Systems
36 Thin QFN-EP*
(6mm x 6mm),
lead free, bulk
-40°C to +85°C
T3666-2
Microwave Links
cdma2000 is a registered trademark of Telecommunications
Industry Association.
36 Thin QFN-EP*
MAX9985ETX+T -40°C to +85°C (6mm x 6mm), T3666-2
lead free, T/R
iDEN is a registered trademark of Motorola, Inc.
cdmaOne is a trademark of CDMA Development Group.
*EP = Exposed paddle.
T = Tape-and-reel package.
+Denotes lead-free and RoHS compliant.
________________________________________________________________ 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.
Dual, SiGe, High-Linearity, 700MHz to 1000MHz
Downconversion Mixer with LO Buffer/Switch
ABSOLUTE MAXIMUM RATINGS
CC
V
to GND...........................................................-0.3V to +5.5V
Maximum Junction Temperature Range..........................+150°C
LO1, LO2 to GND ............................................................... 0.3V
Any Other Pins to GND...............................-0.3V to (V + 0.3V)
θ
θ
.................................................................................+38°C/W
...................................................................................7.4°C/W
JA
JC
CC
RFMAIN, RFDIV, and LO_ Input Power..........................+20dBm
RFMAIN, RFDIV Current (RF is DC shorted to GND through
balun)...............................................................................50mA
Storage Temperature Range.............................-65°C to +150°C
Lead Temperature (soldering, 10s) .................................+300°C
Continuous Power Dissipation (T = +70°C) (Note A)
C
36-Pin Thin QFN (derate 26mW/°C above +70°C) .........10.8W
Operating Temperature Range ...........................-40°C to +85°C
MAX985
Note A: T is the temperature on the exposed paddle of the package.
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
(Using the Typical Application Circuit, no input RF or LO signals applied, V
= 4.75V to 5.25V, T = -40°C to +85°C. Typical values
C
CC
are at V
= 5.0V, T = +25°C, unless otherwise noted.)
CC
C
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
Supply Voltage
Supply Current
V
4.75
5
5.25
V
CC
Total supply current (see Table 1 for lower
current settings)
400
440
V
V
(pin 16)
(pin 30)
80
80
CC
CC
I
mA
CC
IFM+/IFM- (total of both)
IFD+/IFD- (total of both)
105
105
LOSEL Input High Voltage
LOSEL Input Low Voltage
LOSEL Input Current
V
2
V
V
IH
V
0.8
IL
I
and I
-10
+10
µA
IH
IL
AC ELECTRICAL CHARACTERISTICS
(Using the Typical Application Circuit, V
= 4.75V to 5.25V, RF and LO ports are driven from 50Ω sources, P = -3dBm to +3dBm,
CC
LO
P
V
= -5dBm, f = 820MHz to 920MHz, f = 670MHz to 865MHz, f = 100MHz, f > f , T = -40°C to +85°C. Typical values are at
RF
CC
RF LO IF RF LO C
= 5.0V, P = -5dBm, P = 0dBm, f = 870MHz, f = 770MHz, f = 100MHz, T = +25°C, unless otherwise noted.) (Note 1)
RF
LO
RF
LO
IF
C
PARAMETER
SYMBOL
CONDITIONS
MIN
700
570
TYP
MAX
1000
865
UNITS
MHz
RF Frequency
LO Frequency
f
(Note 2)
(Note 2)
RF
LO
f
MHz
IF matching components affect the IF
frequency range (Note 2)
IF Frequency
f
50
250
MHz
IF
LO Drive
P
(Note 3)
(Note 6)
-3
+3
dBm
dB
LO
Conversion Gain
G
4.5
6
7.5
C
Gain Variation over Temperature
-0.012
dB/°C
Flatness over any one of three frequency bands:
f
RF
f
RF
f
RF
= 824MHz to 849MHz
= 869MHz to 894MHz
= 880MHz to 915MHz
Conversion Gain Flatness
0.1
dB
2
_______________________________________________________________________________________
Dual, SiGe, High-Linearity, 700MHz to 1000MHz
Downconversion Mixer with LO Buffer/Switch
MAX985
AC ELECTRICAL CHARACTERISTICS (continued)
(Using the Typical Application Circuit, V
= 4.75V to 5.25V, RF and LO ports are driven from 50Ω sources, P = -3dBm to +3dBm,
CC
LO
P
V
= -5dBm, f = 820MHz to 920MHz, f = 670MHz to 865MHz, f = 100MHz, f > f , T = -40°C to +85°C. Typical values are at
RF
CC
RF LO IF RF LO C
= 5.0V, P = -5dBm, P = 0dBm, f = 870MHz, f = 770MHz, f = 100MHz, T = +25°C, unless otherwise noted.) (Note 1)
RF
LO
RF
LO
IF
C
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
Noise Figure, Single Sideband
NF
f
= 190MHz, no blockers present (Note 3)
10.5
13
dB
IF
+11dBm blocker tone applied to RF port at
961MHz, f = 860MHz, f = 670MHz,
Noise Figure under Blocking
Condition
RF
LO
21
26
dB
f
f
= 190MHz,
= 291MHz (Notes 3, 4)
IFDESIRED
BLOCKER
Input Compression Point
Output Compression Point
P
16.2
21.2
dBm
dBm
1dB
OP
18.5
1dB
P
= -5dBm, f
=
P
P
= +8dBm
0.1
RF
RF
BLOCKER
BLOCKER
Small-Signal Compression under
Blocking Conditions
870MHz, f
= 871MHz
dB
BLOCKER
= +11dBm
0.25
f
P
-f
= 1MHz, f = 100MHz,
RF1 RF2 IF
Third-Order Input Intercept Point
IIP3
28.5
-0.01
34.5
dBm
dB/°C
dBm
= -5dBm/tone
RF
Third-Order Input Intercept Point
Variation over Temperature
Third-Order Output Intercept
Point
P
= -5dBm/tone, f = 100MHz,
IF
RF
OIP3
2 x 2
32.0
f
f
-f
= 1MHz (Note 3)
RF1 RF2
= 870MHz, f
P
P
P
P
= -10dBm
= -5dBm
= -10dBm
= -5dBm
63
58
70
60
77
72
85
75
RF
LO
RF
RF
RF
RF
2RF-2LO Spur
= 770MHz, f
820MHz (Note 3)
=
dBc
dBc
dB
SPUR
f
= 870MHz, f
RF
LO
=
SPUR
3RF-3LO Spur
3 x 3
= 770MHz, f
803.3MHz (Note 3)
P
f
f
= +3dBm, P = +3dBm,
LO2
LO1
LO1-to-LO2 Port Isolation
-f
= 1MHz, P = -5dBm,
RF
39
43
LO1 LO2
= 100MHz (Notes 3, 5)
IF
Maximum LO Leakage at RF Port
Maximum 2LO Leakage at RF Port
Maximum LO Leakage at IF Port
Minimum RF-to-IF Isolation
-40
-45
-30
45
-30
-20
-20
dBm
dBm
dBm
dB
30
40
P
= -10dBm, RFMAIN (RFDIV) power
RF
Minimum Channel-to-Channel
Isolation
measured at IFDIV (IFMAIN), relative to
IFMAIN (IFDIV), all unused ports terminated
to 50Ω
47
dB
_______________________________________________________________________________________
3
Dual, SiGe, High-Linearity, 700MHz to 1000MHz
Downconversion Mixer with LO Buffer/Switch
AC ELECTRICAL CHARACTERISTICS (continued)
(Using the Typical Application Circuit, V
= 4.75V to 5.25V, RF and LO ports are driven from 50Ω sources, P = -3dBm to +3dBm,
CC
LO
P
V
= -5dBm, f = 820MHz to 920MHz, f = 670MHz to 865MHz, f = 100MHz, f > f , T = -40°C to +85°C. Typical values are at
RF
CC
RF LO IF RF LO C
= 5.0V, P = -5dBm, P = 0dBm, f = 870MHz, f = 770MHz, f = 100MHz, T = +25°C, unless otherwise noted.) (Note 1)
RF
LO
RF
LO
IF
C
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
50% of LOSEL to IF settled within 2 degrees
(Note 3)
LO Switching Time
0.05
1
µs
RF Input Impedance
LO Input Impedance
IF Output Impedance
RF Input Return Loss
50
50
Ω
Ω
MAX985
Differential
200
24
Ω
LO on and IF terminated
LO port selected
dB
35
LO Input Return Loss
IF Return Loss
dB
dB
LO port unselected
RF terminated in 50Ω
36
20
Note 1: All limits reflect losses of external components. Output measurements taken at IF outputs of the Typical Application Circuit.
Note 2: Performance is guaranteed for f = 820MHz to 920MHz, f = 670MHz to 865MHz, and f = 100MHz. Operation outside
RF
LO
IF
this range is possible, but with degraded performance of some parameters. See the Typical Operating Characteristics.
Note 3: Guaranteed by design and characterization.
Note 4: Measured with external LO source noise filtered so the noise floor is -174dBm/Hz. This specification reflects the effects of all
SNR degradations in the mixer including the LO noise, as defined in Maxim Application Note 2021.
Note 5: Measured at IF port at IF frequency. LOSEL may be in any logic state.
Note 6: Performance at T = -40°C is guaranteed by design.
C
4
_______________________________________________________________________________________
Dual, SiGe, High-Linearity, 700MHz to 1000MHz
Downconversion Mixer with LO Buffer/Switch
MAX985
Typical Operating Characteristics
(Using the Typical Application Circuit, V
wise noted.)
= 5.0V, P = 0dBm, P = -5dBm, f > f , f = 100MHz, T = +25°C, unless other-
CC
LO
RF
RF
LO IF
C
CONVERSION GAIN vs. RF FREQUENCY
CONVERSION GAIN vs. RF FREQUENCY
CONVERSION GAIN vs. RF FREQUENCY
8
8
7
6
5
4
8
7
6
5
4
T
= -30°C
C
7
6
5
4
P
LO
= -3dBm, 0dBm, +3dBm
V
CC
= 4.75V, 5.0V, 5.25V
T
= +85°C
T
= +25°C
C
C
700
800
900
1000
700
800
900
1000
700
800
900
1000
1000
1000
RF FREQUENCY (MHz)
RF FREQUENCY (MHz)
RF FREQUENCY (MHz)
INPUT IP3 vs. RF FREQUENCY
INPUT IP3 vs. RF FREQUENCY
INPUT IP3 vs. RF FREQUENCY
30
29
28
27
26
25
24
30
29
28
27
26
25
24
30
29
28
27
26
25
24
V
= 5.0V
CC
V
= 4.75V
T
= +85°C
CC
C
V
= 5.25V
CC
T
= +25°C
C
P
= -3dBm, 0dBm, +3dBm
LO
T
= -30°C
C
700
800
900
1000
700
800
900
1000
700
800
900
RF FREQUENCY (MHz)
RF FREQUENCY (MHz)
RF FREQUENCY (MHz)
NOISE FIGURE vs. RF FREQUENCY
NOISE FIGURE vs. RF FREQUENCY
NOISE FIGURE vs. RF FREQUENCY
14
13
12
11
10
9
14
13
12
11
10
9
14
13
12
11
10
9
T
= +85°C
C
V
= 5.25V
CC
V
= 4.75V
CC
P
= -3dBm, 0dBm, +3dBm
V
= 5.0V
LO
CC
T
= +25°C
C
T
= -30°C
C
8
8
8
7
7
7
700
800
900
1000
700
800
900
1000
700
800
900
RF FREQUENCY (MHz)
RF FREQUENCY (MHz)
RF FREQUENCY (MHz)
_______________________________________________________________________________________
5
Dual, SiGe, High-Linearity, 700MHz to 1000MHz
Downconversion Mixer with LO Buffer/Switch
Typical Operating Characteristics (continued)
(Using the Typical Application Circuit, V
wise noted.)
= 5.0V, P = 0dBm, P = -5dBm, f > f , f = 100MHz, T = +25°C, unless other-
CC
LO
RF
RF
LO IF
C
2RF-2LO RESPONSE vs. RF FREQUENCY
2RF-2LO RESPONSE vs. RF FREQUENCY
2RF-2LO RESPONSE vs. RF FREQUENCY
80
80
75
70
65
60
55
50
80
75
70
65
60
55
50
T
= +85°C
P
= -5dBm
P
= -5dBm
= 0dBm
P
= +3dBm
= -3dBm
C
RF
RF
P
= -5dBm
RF
LO
LO
75
70
65
60
55
50
MAX985
T
= -30°C
V
CC
= 4.75V, 5.0V, 5.25V
C
P
T
= +25°C
C
P
LO
700
800
900
1000
700
800
900
1000
700
800
900
1000
RF FREQUENCY (MHz)
RF FREQUENCY (MHz)
RF FREQUENCY (MHz)
3RF-3LO RESPONSE vs. RF FREQUENCY
3RF-3LO RESPONSE vs. RF FREQUENCY
3RF-3LO RESPONSE vs. RF FREQUENCY
95
85
75
65
55
95
85
75
65
55
95
85
75
65
55
P
= -5dBm
P
= -5dBm
RF
P
= -5dBm
RF
RF
T
= +25°C
C
V
= 5.0V
T
= +85°C
CC
C
V
= 4.75V
CC
P
LO
= -3dBm, 0dBm, +3dBm
V
= 5.25V
CC
T
= -30°C
C
700
800
900
1000
700
800
900
1000
700
800
900
1000
RF FREQUENCY (MHz)
RF FREQUENCY (MHz)
RF FREQUENCY (MHz)
INPUT P
vs. RF FREQUENCY
1dB
INPUT P
vs. RF FREQUENCY
INPUT P
vs. RF FREQUENCY
1dB
1dB
19
18
17
16
15
14
13
19
18
17
16
15
14
13
19
18
17
16
15
14
13
V
= 5.25V
CC
T
= +85°C
C
P
= -3dBm, 0dBm, +3dBm
V
= 5.0V
LO
CC
T
= -30°C
C
V
= 4.75V
CC
T
= +25°C
C
700
800
900
1000
1100
1200
700
800
900
1000
1100
1200
700
800
900
1000
1100
1200
RF FREQUENCY (MHz)
RF FREQUENCY (MHz)
RF FREQUENCY (MHz)
6
_______________________________________________________________________________________
Dual, SiGe, High-Linearity, 700MHz to 1000MHz
Downconversion Mixer with LO Buffer/Switch
MAX985
Typical Operating Characteristics (continued)
(Using the Typical Application Circuit, V
wise noted.)
= 5.0V, P = 0dBm, P = -5dBm, f > f , f = 100MHz, T = +25°C, unless other-
CC
LO
RF
RF
LO IF
C
CHANNEL ISOLATION vs. RF FREQUENCY
CHANNEL ISOLATION vs. RF FREQUENCY
CHANNEL ISOLATION vs. RF FREQUENCY
60
60
55
50
45
40
35
30
60
55
50
45
40
35
30
55
50
45
P
LO
= -3dBm, 0dBm, +3dBm
V
CC
= 4.75V, 5.0V, 5.25V
T = -30°C
C
,
+25°C
,
+85°C
40
35
30
700
800
900
1000
700
800
900
1000
700
800
900
1000
RF FREQUENCY (MHz)
RF FREQUENCY (MHz)
RF FREQUENCY (MHz)
LO LEAKAGE AT IF PORT vs. LO FREQUENCY
LO LEAKAGE AT IF PORT vs. LO FREQUENCY
LO LEAKAGE AT IF PORT vs. LO FREQUENCY
-10
-10
-10
-15
-20
-25
-30
-35
-40
-15
-20
-25
-30
-35
-40
-15
-20
-25
-30
-35
-40
T
T
= +25°C
= +85°C
C
C
V
= 5.25V
CC
P
= 0dBm
LO
T
= -30°C
C
P
= +3dBm
V
= 5.0V
CC
LO
V
= 4.75V
700
CC
P
= -3dBm
LO
600
650
700
750
800
850
900
600
650
700
750
800
850
900
600
650
750
800
850
900
LO FREQUENCY (MHz)
LO FREQUENCY (MHz)
LO FREQUENCY (MHz)
RF-TO-IF ISOLATION
vs. RF FREQUENCY
RF-TO-IF ISOLATION
vs. RF FREQUENCY
RF-TO-IF ISOLATION
vs. RF FREQUENCY
60
55
50
45
40
35
30
60
55
50
45
40
35
30
60
55
50
45
40
35
30
T
= +85°C
C
T
= +25°C
C
V
CC
= 4.75V, 5.0V, 5.25V
P
LO
= -3dBm, 0dBm, +3dBm
T
= -30°C
C
700
800
900
1000
700
800
900
1000
700
800
900
1000
RF FREQUENCY (MHz)
RF FREQUENCY (MHz)
RF FREQUENCY (MHz)
_______________________________________________________________________________________
7
Dual, SiGe, High-Linearity, 700MHz to 1000MHz
Downconversion Mixer with LO Buffer/Switch
Typical Operating Characteristics (continued)
(Using the Typical Application Circuit, V
wise noted.)
= 5.0V, P = 0dBm, P = -5dBm, f > f , f = 100MHz, T = +25°C, unless other-
CC
LO
RF
RF
LO IF
C
LO LEAKAGE AT RF PORT
vs. LO FREQUENCY
LO LEAKAGE AT RF PORT
vs. LO FREQUENCY
LO LEAKAGE AT RF PORT
vs. LO FREQUENCY
-20
-20
-30
-40
-50
-60
-20
-30
-40
-50
-60
8
-30
T
= +25°C
T
= -30°C
C
C
-40
-50
-60
V
= 4.75V, 5.0V, 5.25V
CC
P
= -3dBm, 0dBm, +3dBm
LO
T
= +85°C
C
500 600 700 800 900 1000 1100 1200
LO FREQUENCY (MHz)
500 600 700 800 900 1000 1100 1200
LO FREQUENCY (MHz)
500 600 700 800 900 1000 1100 1200
LO FREQUENCY (MHz)
2LO LEAKAGE AT RF PORT
vs. LO FREQUENCY
2LO LEAKAGE AT RF PORT
vs. LO FREQUENCY
2LO LEAKAGE AT RF PORT
vs. LO FREQUENCY
-10
-20
-30
-40
-50
-60
-10
-20
-30
-40
-50
-60
-10
-20
-30
-40
-50
-60
P
= 0dBm
T
= +25°C
LO
C
P
= -3dBm
T
= +85°C
LO
C
V
= 4.75V, 5.0V, 5.25V
CC
P
= +3dBm
LO
T
= -30°C
C
500 600 700 800 900 1000 1100 1200
LO FREQUENCY (MHz)
500 600 700 800 900 1000 1100 1200
LO FREQUENCY (MHz)
500 600 700 800 900 1000 1100 1200
LO FREQUENCY (MHz)
LO SWITCH ISOLATION
vs. RF FREQUENCY
LO SWITCH ISOLATION
vs. RF FREQUENCY
LO SWITCH ISOLATION
vs. RF FREQUENCY
50
45
40
35
30
50
45
40
35
30
50
45
40
35
30
T
= -30°C
C
V
= 4.75V, 5.0V, 5.25V
T
= +85°C
P
= -3dBm, 0dBm, 3dBm
LO
CC
C
T
= +25°C
C
600
700
800
900 1000 1100 1200
600
700
800
900 1000 1100 1200
600
700
800
900 1000 1100 1200
RF FREQUENCY (MHz)
RF FREQUENCY (MHz)
RF FREQUENCY (MHz)
8
_______________________________________________________________________________________
Dual, SiGe, High-Linearity, 700MHz to 1000MHz
Downconversion Mixer with LO Buffer/Switch
MAX985
Typical Operating Characteristics (continued)
(Using the Typical Application Circuit, V
wise noted.)
= 5.0V, P = 0dBm, P = -5dBm, f > f , f = 100MHz, T = +25°C, unless other-
CC
LO
RF
RF
LO IF
C
RF PORT RETURN LOSS
vs. RF FREQUENCY
IF PORT RETURN LOSS
vs. IF FREQUENCY
LO SELECTED RETURN LOSS
vs. LO FREQUENCY
0
10
20
30
40
50
0
0
5
5
V
= 4.75V, 5.0V, 5.25V
P
= +3dBm
LO
CC
10
10
15
20
25
30
P
= -3dBm, 0dBm, +3dBm
LO
P
= 0dBm
LO
15
20
25
30
P
= -3dBm
LO
500 600 700 800 900 1000 1100 1200
RF FREQUENCY (MHz)
500 600 700 800 900 1000 1100 1200
LO FREQUENCY (MHz)
0
100
200
300
400
500
IF FREQUENCY (MHz)
LO UNSELECTED RETURN LOSS
vs. LO FREQUENCY
SUPPLY CURRENT
vs. TEMPERATURE (T )
CONVERSION GAIN vs. RF FREQUENCY
(VARIOUS LO AND IF BUFFER BIAS)
C
7.0
6.5
6.0
5.5
0
430
420
410
400
390
380
370
360
V
= 5.25V
CC
10
20
30
40
50
3
2
0
6
4
1
5
V
= 5.0V
CC
P
= -3dBm, 0dBm, +3dBm
LO
V
= 4.75V
CC
7
8, 9
SEE TABLE 1 FOR R1, R2, AND I VALUES.
CC
500 600 700 800 900 1000 1100 1200
LO FREQUENCY (MHz)
-35
-15
5
25
45
65
85
700
800
900
1000
TEMPERATURE (°C)
RF FREQUENCY (MHz)
INPUT IP3 vs. RF FREQUENCY
(VARIOUS LO AND IF BUFFER BIAS)
2RF-2LO RESPONSE vs. RF FREQUENCY
(VARIOUS LO AND IF BUFFER BIAS)
3RF-3LO RESPONSE vs. RF FREQUENCY
(VARIOUS LO AND IF BUFFER BIAS)
30
29
28
27
26
25
24
23
22
21
20
85
80
75
70
65
60
90
85
80
75
70
65
60
55
P
= -5dBm
6
3
1
1
RF
P
= -5dBm
3
0
RF
2
2
0
4
2
6
0
5
6
4
3
5
7
8
5
9
8
9
7
8
7
SEE TABLE 1 FOR R1, R2, AND I VALUES.
SEE TABLE 1 FOR R1, R2, AND I VALUES.
SEE TABLE 1 FOR R1, R2, AND I VALUES.
CC
CC
CC
700
800
900
1000
700
800
900
1000
700
800
900
1000
RF FREQUENCY (MHz)
RF FREQUENCY (MHz)
RF FREQUENCY (MHz)
_______________________________________________________________________________________
9
Dual, SiGe, High-Linearity, 700MHz to 1000MHz
Downconversion Mixer with LO Buffer/Switch
Typical Operating Characteristics (continued)
(Using the Typical Application Circuit, V
wise noted.)
= 5.0V, P = 0dBm, P = -5dBm, f > f , f = 100MHz, T = +25°C, unless other-
CC
LO
RF
RF
LO IF
C
INPUT P
vs. RF FREQUENCY
1dB
RF-TO-IF ISOLATION vs. RF FREQUENCY
(VARIOUS VALUES OF L3 AND L6)
LO LEAKAGE AT IF PORT vs. LO FREQUENCY
(VARIOUS VALUES OF L3 AND L6)
(VARIOUS LO AND IF BUFFER BIAS)
18
17
16
15
14
13
12
11
10
9
70
60
50
40
30
20
-10
0
L = 15nH
L = 30nH
-15
-20
-25
-30
-35
-40
0Ω
MAX985
1, 2, 3
4, 5, 6
L = 7.5nH
L = 7.5nH
L = 30nH
650
L = 15nH
7, 8, 9
0Ω
SEE TABLE 1 FOR R1, R2, AND I VALUES.
CC
8
700
800
900
1000
700
800
900
1000
600
700
750
800
850
900
RF FREQUENCY (MHz)
RF FREQUENCY (MHz)
LO FREQUENCY (MHz)
Table 1. DC Current vs. Bias Resistor
Settings
BIAS
CONDITION
DC CURRENT
(mA)
R1 AND R4
VALUES (Ω)
R2 AND R5
VALUES (Ω)
0
1
2
3
4
5
6
7
8
9
397.8
345.0
316.5
297.5
301.2
271.7
252.2
260.1
230.5
211.5
1070
1400
1400
1400
1910
1910
1910
2800
2800
2800
1100
1100
1620
2210
1100
1620
2210
1100
1620
2210
10 ______________________________________________________________________________________
Dual, SiGe, High-Linearity, 700MHz to 1000MHz
Downconversion Mixer with LO Buffer/Switch
MAX985
Pin Description
PIN
1
NAME
RFMAIN
TAPMAIN
FUNCTION
Main Channel RF input. Internally matched to 50Ω. Requires an input DC-blocking capacitor.
Main Channel Balun Center Tap. Bypass to GND with capacitors close to the pin.
2
3, 5, 7, 12,
20, 22, 24,
25, 26, 34
GND
Ground
4, 6, 10, 16,
21, 30, 36
Power Supply. Connect bypass capacitors as close to the pin as possible (see the Typical
Application Circuit).
V
CC
8
9
TAPDIV
RFDIV
Diversity Channel Balun Center Tap. Bypass to GND with capacitors close to the pin.
Diversity Channel RF Input. Internally matched to 50Ω. Requires an input DC-blocking capacitor.
IF Diversity Amplifier Bias Control. Connect a 1.07kΩ resistor from this pin to ground to set the bias
current for the diversity IF amplifier (see the Typical Operating Characteristics for typical performance
versus resistor value).
11
13, 14
15
IFDBIAS
IFD+, IFD-
LEXTD
Diversity Mixer Differential IF Output. Connect pullup inductors from each of these pins to V (see
CC
the Typical Application Circuit).
Connect a 30nH inductor from this pin to ground to increase the RF-to-IF and LO-to-IF isolation.
Connect this pin to ground if isolations can be degraded (see the Typical Operating Characteristics
for typical degradation).
LO Diversity Amplifier Bias Control. Connect a 1.1kΩ resistor from this pin to ground to set the bias
current for the diversity LO amplifier (see the Typical Operating Characteristics for typical
performance versus resistor value).
17
LODBIAS
18, 28
19
N.C.
LO1
No Connection. Not internally connected.
Local Oscillator 1 Input. This input is internally matched to 50Ω. Requires an input DC-blocking capacitor.
Local Oscillator Select. Set this pin to high to select LO1. Set low to select LO2.
Local Oscillator 2 Input. This input is internally matched to 50Ω. Requires an input DC-blocking capacitor.
23
LOSEL
LO2
27
LO Main Amplifier Bias Control. Connect a 1.1kΩ resistor from this pin to ground to set the bias
current for the main LO amplifier (see the Typical Operating Characteristics for typical performance
versus resistor value).
29
31
LOMBIAS
LEXTM
Connect a 30nH inductor from this pin to ground to increase the RF-IF and LO-IF isolation. Connect
this pin to ground if isolations can be degraded (see the Typical Operating Characteristics for typical
degradation).
Main Mixer Differential IF Output. Connect pullup inductors from each of these pins to V (see the
CC
Typical Application Circuit).
32, 33
35
IFM-, IFM+
IFMBIAS
EP
IF Main Amplifier Bias Control. Connect a 1.07kΩ resistor from this pin to ground to set the bias current for
the main IF amplifier (see the Typical Operating Characteristics for typical performance vs. resistor value).
Exposed Paddle. Solder the exposed paddle to the ground plane using multiple vias. This paddle
affects RF performance and provides heat dissipation.
—
______________________________________________________________________________________ 11
Dual, SiGe, High-Linearity, 700MHz to 1000MHz
Downconversion Mixer with LO Buffer/Switch
(LOSEL), where logic-high selects LO1 and logic-low
Detailed Description
selects LO2. LO1 and LO2 inputs are internally
The MAX9985 is a dual-channel downconverter
matched to 50Ω, requiring only an 82pF DC-blocking
capacitor. To avoid damage to the part, voltage MUST
designed to provide 6dB of conversion gain, +28.5dBm
input IP3, and +16.2dBm 1dB input compression point,
be applied to V
before digital logic is applied to
CC
with a 10.5dB NF.
LOSEL. Alternatively, a 1kΩ resistor can be placed in
In addition to its high-linearity performance, the
MAX9985 achieves a high level of component integra-
tion. The device integrates two double-balanced active
mixers for two-channel downconversion. Both the main
and diversity channels include a balun and matching
circuitry to allow 50Ω single-ended interfaces to the RF
ports and the two LO ports. An integrated single-pole,
double-throw (SPDT) switch provides 50ns switching
time between the two LO inputs with 43dB of LO-to-LO
isolation and a -40dBm of LO leakage at the RF port.
Furthermore, the integrated LO buffers provide a high
drive level to each mixer core, reducing the LO drive
required at the MAX9985’s inputs to a -3dBm to +3dBm
range. The IF ports for both channels incorporate differ-
ential outputs for downconversion, which is ideal for
providing enhanced IIP2 performance.
series at the LOSEL to limit the input current in applica-
tions where LOSEL is applied before V
.
CC
The main and diversity channels incorporate a two-
stage LO buffer that allows for a wide-input power
range for the LO drive. All guaranteed specifications
are for an LO signal power from -3dBm to +3dBm. The
on-chip low-loss baluns, along with LO buffers, drive
the double-balanced mixers. All interfacing and match-
ing components from the LO inputs to the IF outputs
are integrated on-chip.
MAX985
High-Linearity Mixer
The core of the MAX9985 dual-channel downconverter
consists of two double-balanced, high-performance
passive mixers. Exceptional linearity is provided by the
large LO swing from the on-chip LO buffers. When com-
bined with the integrated IF amplifiers, the cascaded
IIP3, 2RF-2LO rejection, and NF performance are typi-
cally +28.5dBm, 77dBc, and 10.5dB, respectively.
Dual-channel downconversion makes the MAX9985
ideal for diversity receiver applications. In addition,
specifications are guaranteed over broad frequency
ranges to allow for use in GSM 850/950, 2G/2.5G
EDGE, WCDMA, cdma2000, and iDEN base stations.
The MAX9985 is specified to operate over a 700MHz to
1000MHz RF input range, a 570MHz to 865MHz LO
range, and a 50MHz to 250MHz IF range. The external
IF components set the lower frequency range (see the
Typical Operating Characteristics for details).
Differential IF
The MAX9985 has a 50MHz to 250MHz IF frequency
range, where the low-end frequency depends on the
frequency response of the external IF components. Note
that these differential ports are ideal for providing
enhanced IIP2 performance. Single-ended IF applica-
tions require a 4:1 (impedance ratio) balun to transform
the 200Ω differential IF impedance to a 50Ω single-
ended system. After the balun, the IF return loss is bet-
ter than 20dB. The user can use a differential IF
amplifier on the mixer IF ports, but a DC block is
required on both IFD+/IFD- and IFM+/IFM- ports to keep
external DC from entering the IF ports of the mixer.
RF Port and Balun
The RF input ports to both the main and diversity chan-
nels are internally matched to 50Ω, requiring no exter-
nal matching components. A DC-blocking capacitor is
required as the input is internally DC-shorted to ground
through the on-chip balun. The RF port return loss is
typically 15dB over the entire 700MHz to 1000MHz RF
frequency range.
Applications Information
Input and Output Matching
The RF and LO inputs are internally matched to 50Ω.
No matching components are required. Return loss at
the RF port is typically 15dB over the entire input range
and return loss at the LO ports are typically 25dB. RF
and LO inputs require only DC-blocking capacitors for
interfacing.
LO Inputs, Buffer, and Balun
The MAX9985 is optimized for a 570MHz to 865MHz
LO frequency range. As an added feature, the
MAX9985 includes an internal LO SPDT switch for use
in frequency-hopping applications. The switch selects
one of the two single-ended LO ports, allowing the
external oscillator to settle on a particular frequency
before it is switched in. LO switching time is typically
less than 50ns, which is more than adequate for typical
GSM applications. If frequency hopping is not
employed, simply set the switch to either of the LO
inputs. The switch is controlled by a digital input
The IF output impedance is 200Ω (differential). For
evaluation, an external low-loss 4:1 (impedance ratio)
balun transforms this impedance to a 50Ω single-ended
output (see the Typical Application Circuit).
12 ______________________________________________________________________________________
Dual, SiGe, High-Linearity, 700MHz to 1000MHz
Downconversion Mixer with LO Buffer/Switch
MAX985
LO Buffer Bias Resistors
Bias currents for the two on-chip LO buffers is opti-
mized by fine-tuning the off-chip resistors on LODBIAS
(pin 17) and LOMBIAS (pin 29). The current in the
buffer amplifiers is reduced by increasing the value of
these resistors, but performance may degrade. See the
Typical Operating Characteristics for key performance
parameters versus this resistor value. Doubling the
value of these resistors reduces the total chip current
by approximately 50mA (see Table 1).
Power-Supply Bypassing
Proper voltage-supply bypassing is essential for high-
frequency circuit stability. Bypass each V
pin and
CC
TAPMAIN/TAPDIV with the capacitors shown in the
Typical Application Circuit (see Table 2 for component
values). Place the TAPMAIN/TAPDIV bypass capacitor
to ground within 100 mils of the pin.
Table 2. Component Values
COMPONENT
C1, C2, C7, C8
C3, C6
VALUE
DESCRIPTION
IF Amplifier Bias Resistors
Bias currents for the two on-chip IF amplifiers are opti-
mized by fine-tuning the off-chip resistors on IFDBIAS
(pin 11) and IFMBIAS (pin 35). The current in the IF
amplifiers is decreased by raising the value of these
resistors, but performance may degrade. See the
Typical Operating Characteristics for key performance
parameters versus this resistor value. Doubling the
value of this resistor reduces the current in each IF
amplifier from 100mA to approximately 50mA (see
Table 1).
39pF
Microwave capacitors (0402)
0.033µF Microwave capacitors (0603)
Not used
C4, C5
—
C9, C13, C15,
C17, C18
0.01µF Microwave capacitors (0402)
C10, C11, C12,
C19, C20, C21
150pF
82pF
Microwave capacitors (0603)
Microwave capacitors (0402)
C14, C16
Wire-wound high-Q inductors
(0805)
L1, L2, L4, L5
560nH
LEXT Inductor
Short LEXT_ to ground using a 0Ω resistor. For applica-
tions requiring improved RF-to-IF and LO-to-IF isolation,
LEXT_ can be used by connecting a low-ESR inductor
from LEXT_ to GND. See the Typical Operating
Characteristics on RF-to-IF port isolation and LO-to-IF
port leakage for various inductor values. The load
impedance presented to the mixer must be such that
any capacitance from both IF- and IF+ to ground do not
exceed several picofarads to ensure stable operating
conditions.
Wire-wound high-Q inductors
(0603)
L3, L6
30nH
R1, R4
R2, R5
R3, R6
1.07kΩ
1.1kΩ
0Ω
1% resistors (0402)
1% resistors (0402)
Resistors (1206)
Transformers (200:50)
Mini-Circuits TC4-1W-7A
T1, T2
U1
4:1
—
MAX9985 IC
Approximately 100mA flows through LEXT_, so it is
important to use a low-DCR wire-wound inductor.
Exposed Paddle RF/Thermal
Considerations
The exposed paddle (EP) of the MAX9985’s 36-pin thin
QFN-EP package provides a low thermal-resistance
path to the die. It is important that the PCB on which the
MAX9985 is mounted be designed to conduct heat
from the EP. In addition, provide the EP with a low-
inductance path to electrical ground. The EP MUST be
soldered to a ground plane on the PCB, either directly
or through an array of plated via holes.
Layout Considerations
A properly designed PCB is an essential part of any
RF/microwave circuit. Keep RF signal lines as short as
possible to reduce losses, radiation, and inductance.
For the best performance, route the ground pin traces
directly to the exposed paddle under the package. The
PCB exposed paddle MUST be connected to the
ground plane of the PCB. It is suggested that multiple
vias be used to connect this paddle to the lower-level
ground planes. This method provides a good RF/ther-
mal-conduction path for the device. Solder the exposed
paddle on the bottom of the device package to the
PCB. Refer to the MAX9985 Evaluation Kit as a refer-
ence for board layout. Gerber files are available upon
request at www.maxim-ic.com.
______________________________________________________________________________________ 13
Dual, SiGe, High-Linearity, 700MHz to 1000MHz
Downconversion Mixer with LO Buffer/Switch
Typical Application Circuit
C19
IF MAIN
OUTPUT
T1
L1
L2
V
CC
C21
R3
MAX985
4:1
C20
V
CC
V
CC
R1
C17
L3
C18
R2
36
35
34
33
32
31
30
29
28
RFMAIN
LO2
RF MAIN
INPUT
27
1
2
3
4
5
6
7
8
9
LO2
C1
C16
GND
GND
GND
TAPMAIN
GND
26
25
24
23
22
21
20
19
C3
C2
MAX9985
V
CC
V
CC
C4
GND
LOSEL
GND
LO
SELECT
V
CC
V
CC
V
CC
C5
C6
V
GND
TAPDIV
RFDIV
CC
C15
C7
EXPOSED
PADDLE
GND
LO1
RF DIV
INPUT
LO1
C8
C14
10
11
12
13
14
15
16
17
18
R5
V
CC
V
CC
L6
R4
C13
C9
C11
T2
L5
V
CC
C12
R6
IF DIV
OUTPUT
L4
4:1
C10
14 ______________________________________________________________________________________
Dual, SiGe, High-Linearity, 700MHz to 1000MHz
Downconversion Mixer with LO Buffer/Switch
MAX985
Pin Configuration/Functional Diagram
TOP VIEW (with
exposed paddle on
the bottom of the
package)
36
35
34
33
32
31
30
29
28
27
26
RFMAIN
TAPMAIN
GND
1
2
3
4
5
6
7
8
9
LO2
GND
MAX9985
25 GND
GND
24
23
V
CC
GND
LOSEL
22 GND
V
CC
21
20
19
V
CC
GND
TAPDIV
RFDIV
EXPOSED
PADDLE
GND
LO1
10
11
12
13
14
15
16
17
18
THIN QFN
6mm x 6mm
Chip Information
PROCESS: SiGe BiCMOS
Package Information
For the latest package outline information, go to
www.maxim-ic.com/packages.
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
© 2007 Maxim Integrated Products
is a registered trademark of Maxim Integrated Products, Inc.
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