19-2416; Rev 2; 3/04
+14dBm to +20dBm LO Buffers/Splitters
with ±1dB Variation
Features
The MAX9987 and MAX9988 LO buffers/splitters each
integrate a passive two-way power splitter with highisolation input and output buffer amplifiers. These
buffers are designed to provide the high output
(+14dBm to +20dBm) necessary to drive the LO inputs
of high-linearity passive mixers, while offering 40dB
reverse isolation to prevent LO pulling. The MAX9987 is
internally matched for the cellular/GSM bands, and the
MAX9988 is matched for the DCS/PCS/UMTS bands.
♦ ±1dB Output Power Variation
The typical application circuit provides a nominal
+17dBm output power with ±1dB variation over supply,
temperature, and input power. With two optional resistors, the output power can be precision set from
+14dBm to +20dBm. The devices offer more than 30dB
output-to-output port isolation, and are offered in 5mm ✕
5mm 20-pin thin QFN packages with exposed paddle.
♦ 160mA Supply Current at +17dBm
♦ +14dBm to +20dBm Adjustable Output Power
♦ Two-Way Power Splitting
♦ 40dB Reverse Isolation
♦ More than 30dB Output-to-Output Isolation
♦ Low Output Noise: -170dBc/Hz at +17dBm
♦ Isolated PLL Output (+3dBm)
Applications
Ordering Information
Cellular/GSM/DCS/PCS/UMTS Base Station
Tx/Rx LO Drive
PINPACKAGE
FREQUENCY
RANGE
MAX9987ETP-T -40°C to 85°C
20 Thin
QFN-EP*
700MHz to
1100MHz
MAX9988ETP-T -40°C to 85°C
20 Thin
QFN-EP*
1500MHz to
2200MHz
PART
TEMP
RANGE
Base Station Main and Diversity Channels
Coherent Receivers
ISM Wireless LAN
Wireless Local Loop
*EP = Exposed paddle.
Local Multipoint Distribution Service
Point-to-Point Systems
Typical Operating Circuit and Block Diagram
PLL BUFFER
TO PLL
PRESCALER
MAX9987
MAX9988
OUTPLL
(+3dBm)
IN
(+7dBm)
RF INPUT
(1)
OUTPUT AMP
(1)
OUT1
(+17dBm)
RF INPUT
(2)
INPUT AMP
RF LO
IF OUTPUT
(1)
PASSIVE TWO-WAY
POWER SPLITTER
OUT2
(+17dBm)
IF OUTPUT
(2)
BIAS
OUTPUT AMP
(2)
BIASIN
BIASOUT
BIAS
CONTROL
NETWORK
________________________________________________________________ Maxim Integrated Products
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.
1
MAX9987/MAX9988
General Description
MAX9987/MAX9988
+14dBm to +20dBm LO Buffers/Splitters
with ±1dB Variation
ABSOLUTE MAXIMUM RATINGS
VCC1, VCC2, VCC3,
VCCREF to GND.................................................-0.3V to +6.0V
IN to GND ...................................................-0.3V to (VCC + 0.3V)
OUT1, OUT2,
OUTPLL to GND ......................................-0.3V to (VCC + 0.3V)
REF to GND ......................................................Source/Sink 5mA
INBIAS, OUTBIAS, to GND..................................-0.3V to +0.75V
PLLBIAS ......................................................................Sink 25mA
RF Input Power ...............................................................+20dBm
Continuous Power Dissipation (TA = +70°C)
5mm ✕ 5mm 20-Pin Thin QFN (derate 20mW/°C
above +70°C).............................................................1600mW
θJA ....................................................................................50°C/W
Junction Temperature ......................................................+150°C
Operating Temperature Range ...........................-40°C to +85°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—MAX9987
(Typical Application Circuit, VCC = 4.75V to 5.25V, input and outputs terminated in 50Ω, TA = -40°C to +85°C. Typical specifications
are for VCC = 5.0V and TA = +25°C.) (Note 1)
PARAMETER
Supply Voltage
SYMBOL
CONDITIONS
VCC
MIN
TYP
MAX
UNITS
4.75
5.00
5.25
V
171
mA
Low power setting
(see Table 1 for resistor values)
Supply Current
ICC
Nominal power setting
(R1, R2, R4, and R5 not installed)
110
139
High power setting
(see Table 1 for resistor values)
155
221
DC ELECTRICAL CHARACTERISTICS—MAX9988
(Typical Application Circuit, VCC = 4.75V to 5.25V, input and outputs terminated in 50Ω, TA = -40°C to +85°C. Typical specifications
are for VCC = 5.0V and TA = +25°C.) (Note 1)
PARAMETER
Supply Voltage
SYMBOL
CONDITIONS
VCC
MIN
TYP
MAX
UNITS
4.75
5.00
5.25
V
175
mA
Low power setting
(see Table 1 for resistor values)
Supply Current
ICC
Nominal power setting
(R1, R2, R4, and R5 not installed)
High power setting
(see Table 1 for resistor values)
2
120
150
162
229
_______________________________________________________________________________________
+14dBm to +20dBm LO Buffers/Splitters
with ±1dB Variation
(Typical Application Circuit, VCC = 4.75V to 5.25V, 50Ω environment, +4dBm < PIN < +10dBm, 700MHz < fIN < 1100MHz,
TA = -40°C to +85°C, unless otherwise noted. Typical specifications are for VCC = 5.0V, PIN = +7dBm, fIN = 900MHz, and
TA = +25°C, unless otherwise noted.) (Note 1)
PARAMETER
Operating Frequency
Output Power (Main Drivers)
SYMBOL
f
POUTLO
CONDITIONS
MIN
700
TYP
Low power setting, PIN = +4dBm
(see Table 1 for resistor values)
14.3
Nominal power setting,
+4dBm < PIN < +10dBm, 4.75V < VCC <
5.25V, -40°C < TA < +85°C
(R1, R2, R4, and R5 not installed)
17.3
±0.8
High power setting, PIN = +10dBm
(see Table 1 for resistor values)
19.7
Output Power (PLL Driver)
POUTPLL
3.7
Input VSWR
VSWRIN
1.2:1
Output VSWR
VSWROUT
Output-Noise Power Density
PNOISE
MAX
1100
UNITS
MHz
dBm
dBm
1.7:1
VCC = 5.0V, ±100MHz offset
(R1, R2, R4, and R5 not installed)
-152
dBm/Hz
OUT1 to OUT2 Isolation
S23
VCC = 5.0V, nominal power setting
(R1, R2, R4, and R5 not installed)
45
dB
OUT2 to OUT1 Isolation
S32
VCC = 5.0V, nominal power setting
(R1, R2, R4, and R5 not installed)
39
dB
OUT1 to RFIN Isolation
S12
VCC = 5.0V, nominal power setting
(R1, R2, R4, and R5 not installed)
48
dB
OUT2 to RFIN Isolation
S13
VCC = 5.0V, nominal power setting
(R1, R2, R4, and R5 not installed)
50
dB
_______________________________________________________________________________________
3
MAX9987/MAX9988
AC ELECTRICAL CHARACTERISTICS—MAX9987
MAX9987/MAX9988
+14dBm to +20dBm LO Buffers/Splitters
with ±1dB Variation
AC ELECTRICAL CHARACTERISTICS—MAX9988
(Typical Application Circuit, VCC = 4.75V to 5.25V, 50Ω environment, +6dBm < PIN < +12dBm, 1500MHz < fIN < 2200MHz, and
TA = -40°C to +85°C, unless otherwise noted. Typical specifications are for VCC = 5.0V, PIN = +9dBm, fIN = 1800MHz, and
TA = +25°C unless otherwise noted.) (Note 1)
PARAMETER
Operating Frequency
Output Power
(Main Drivers)
Output Power
(PLL Driver)
Input VSWR
Output VSWR
Output-Noise Power Density
SYMBOL
CONDITIONS
f
POUTLO
MIN
TYP
1500
Low power setting, PIN = +6dBm
(see Table 1 for resistor values)
14.2
Nominal power setting,
+6dBm < PIN < +12dBm, 4.75V < VCC <
5.25V, -40°C < TA < +85°C
(R1, R2, R4, and R5 not installed)
17.3
±0.8
High power setting, PIN = +12dBm
(see Table 1 for resistor values)
19.5
POUTPLL
3.6
VSWRIN
1.5:1
VSWROUT
1.4:1
PNOISE
VCC = 5.0V, ±100MHz offset
MAX
UNITS
2200
MHz
dBm
dBm
-152
dBm/Hz
33
dB
OUT1 to OUT2 Isolation
S23
VCC = 5.0V, nominal power setting
(R1, R2, R4, and R5 not installed)
OUT2 to OUT1 Isolation
S32
VCC = 5.0V, nominal power setting
(R1, R2, R4, and R5 not installed)
44
dB
OUT1 to RFIN Isolation
S12
VCC = 5.0V, nominal power setting
(R1, R2, R4, and R5 not installed)
49
dB
OUT2 to RFIN Isolation
S13
VCC = 5.0V, nominal power setting
(R1, R2, R4, and R5 not installed)
47
dB
Note 1: Devices are 100% DC screened and AC production tested for functionality. Data sheet typical specifications are derived
from the average of 30 units from a typical lot, and are tested under the conditions specified for the typical specifications.
4
_______________________________________________________________________________________
+14dBm to +20dBm LO Buffers/Splitters
with ±1dB Variation
MAX9987
SUPPLY CURRENT vs. OUTPUT POWER
OUTMAIN
155
TA = -40°C
150
16
14
13
14
13
12
11
11
140
10
0
5
10
15
20
OUTPUT POWER vs. INPUT POWER, OUTPLL
3
2
TA = -40°C
1
TA = +25°C
0
-1
-2
TA = +85°C
-3
19
OUTPUT POWER (dBm)
4
-5 -4 -3 -2 -1 0 1 2 3 4 5 6 7 8 9 10
INPUT POWER (dBm)
OUTPUT POWER vs. FREQUENCY, OUT2
OUTPUT POWER vs. FREQUENCY, OUT1
20
MAX9987 toc04
5
10
-5 -4 -3 -2 -1 0 1 2 3 4 5 6 7 8 9 10
INPUT POWER (dBm)
TA = -40°C
TA = +25°C
20
19
OUTPUT POWER (dBm)
-5
MAX9987 toc05
-10
18
17
TA = +85°C
16
-5
0
2
4
6
8
10
500
600
700
800
INPUT POWER (dBm)
OPERATING FREQUENCY (MHz)
OUTPUT POWER vs. FREQUENCY, PLL
OUTPUT POWER AND SUPPLY CURRENT
vs. TEMPERATURE
OUTPUT POWER (dBm)
TA = +25°C T = +85°C
A
5
TA = -40°C
4
3
2
1
0
500
600
700
800
900 1000 1100 1200
OPERATING FREQUENCY (MHz)
17
TA = +85°C
16
600
700
900 1000 1100 1200
800
OUTPUT POWER vs. SUPPLY VOLTAGE
162.0
17.8
161.8
17.6
161.6
ICC
17.4
500
OPERATING FREQUENCY (MHz)
MAX9987 toc08
18.0
MAX9987 toc07
6
18
900 1000 1100 1200
161.4
17.2
161.2
17.0
161.0
16.8
160.8
POUT
MAX9987 toc09
18.0
SUPPLY CURRENT (mA)
-2
OUT1, OUT2 OUTPUT POWER (dBm)
-4
TA = -40°C
14
14
-6
TA = +25°C
15
15
-4
TA = +85°C
15
145
OUTPUT POWER (dBm)
OUTPUT POWER (dBm)
16
12
-15
OUTPUT POWER (dBm)
TA = +85°C
15
TA = +25°C
17
17.5
17.0
OUT2
5.5
OUT1
5.0
4.5
16.5
16.0
6.0
4.0
OUTPLL
15.5
3.5
15.0
3.0
16.6
160.6
16.4
160.4
16.2
160.2
14.5
2.5
16.0
160.0
14.0
2.0
-40
-20
0
20
40
60
AMBIENT TEMPERATURE (°C)
80
4.5 4.6 4.7 4.8 4.9 5.0 5.1 5.2 5.3 5.4 5.5
SUPPLY VOLTAGE (V)
_______________________________________________________________________________________
5
PLL OUTPUT POWER (dBm)
160
TA = +25°C
17
TA = -40°C
18
MAX9987 toc06
TA = +25°C AND +85°C
165
19
TA = -40°C
18
MAX9987 toc03
20
OUTPUT POWER (dBm)
170
19
OUTPUT POWER (dBm)
SUPPLY CURRENT (mA)
175
OUTPUT POWER vs. INPUT POWER
OUT2
MAX9987 toc02
20
MAX9987 toc01
180
OUTPUT POWER vs. INPUT POWER
OUT1
MAX9987/MAX9988
Typical Operating Characteristics
(VCC = 5.0V, nominal bias, fIN = 900MHz, PIN = +7dBm, TA = +25°C, unless otherwise noted.) (Shaded regions are outside the
guaranteed operating range, and are provided for reference only.)
Typical Operating Characteristics (continued)
(VCC = 5.0V, nominal bias, fIN = 900MHz, PIN = +7dBm, TA = +25°C, unless otherwise noted.) (Shaded regions are outside the
guaranteed operating range, and are provided for reference only.)
MAX9987
SMALL-SIGNAL GAIN vs. FREQUENCY
OUT2
-10
17
GAIN (dB)
160
PLL BIASED
155
16
OUT1
15
150
VCC = 5.0V
TA = +25°C
PIN = +7dBm
-5
MAX9987 toc12
18
VCC = 5.0V
TA = +25°C
PIN = -15dBm
NOMINAL BIAS
INPUT RETURN LOSS vs. FREQUENCY
0
RETURN LOSS (dB)
MAX9987 toc10
165
SUPPLY CURRENT (mA)
19
MAX9987 toc11
SUPPLY CURRENT vs. SUPPLY VOLTAGE
170
-15
-20
-25
-30
14
-35
13
4.5 4.6 4.7 4.8 4.9 5.0 5.1 5.2 5.3 5.4 5.5
SUPPLY VOLTAGE (V)
-40
0.5
-8
-10
PLL
-14
1.1
0.5
PLL TO IN
-45
-50
0.7
0.8
0.9
1.0
1.1
-40
-45
-50
OUT2 TO IN
-60
-70
0.6
0.7
0.8
0.9
1.0
0.5
1.1
PLL TO OUT_
-40
-45
0.8
0.9
FREQUENCY (GHz)
-140
±100MHz OFFSET
NOISE POWER (dBm/Hz)
ISOLATION (dB)
-30
VCC = 5.0V
TA = +25°C
PIN = +7dBm
0.7
OUTPUT NOISE POWER
vs. INPUT POWER
MAX9987 toc16
-25
OUT2 TO PLL
-50
-145
-150
-155
OUT1 TO PLL
-60
0.6
FREQUENCY (GHz)
PLL ISOLATION vs. FREQUENCY
-55
OUT2 TO OUT1
-65
0.5
-20
-65
-160
-70
0.5
0.6
0.7
0.8
0.9
FREQUENCY (GHz)
6
1.0
1.1
-55
OUT1 TO IN
FREQUENCY (GHz)
-35
OUT1 TO OUT2
-35
-70
0.6
1.0
VCC = 5.0V
TA = +25°C
PIN = +7dBm
-25
-65
-20
0.9
-30
-55
-18
0.8
OUT1 AND OUT2 ISOLATION vs. FREQUENCY
-35
-40
0.7
-20
MAX9987 toc14
-30
-60
0.5
0.6
FREQUENCY (GHz)
VCC = 5.0V
TA = +25°C
PIN = +7dBm
-25
OUT2
-16
1.0
ISOLATION (dB)
OUT1
-12
0.9
IN ISOLATION vs. FREQUENCY
ISOLATION (dB)
-4
-6
0.8
-20
MAX9987 toc13
VCC = 5.0V
TA = +25°C
PIN = +7dBm
-2
0.7
FREQUENCY (GHz)
OUTPUT RETURN LOSS vs. FREQUENCY
0
0.6
MAX9987 toc15
140
MAX9987 toc17
PLL NOT BIASED
145
RETURN LOSS (dB)
MAX9987/MAX9988
+14dBm to +20dBm LO Buffers/Splitters
with ±1dB Variation
1.1
4
5
6
7
8
9
INPUT POWER (dBm)
_______________________________________________________________________________________
10
1.0
1.1
+14dBm to +20dBm LO Buffers/Splitters
with ±1dB Variation
MAX9988
160
TA = +25°C
155
TA = -40°C
150
16
15
TA = +85°C
14
13
13
11
10
10
15
OUTPUT POWER vs. INPUT POWER, OUTPLL
OUTPUT POWER vs. FREQUENCY, OUT1
TA = -40°C
0
-1
-2
OUTPUT POWER vs. FREQUENCY, OUT2
20
18
18
17
16
TA = +25°C
15
TA = +85°C
14
13
17
16
13
12
-4
11
11
-5
10
2
4
6
8
10
10
1500 1600 1700 1800 1900 2000 2100 2200
1500 1600 1700 1800 1900 2000 2100 2200
OPERATING FREQUENCY (MHz)
OPERATING FREQUENCY (MHz)
INPUT POWER (dBm)
OUTPUT POWER AND SUPPLY CURRENT
vs. TEMPERATURE
OUTPUT POWER vs. FREQUENCY, OUTPLL
TA = +25°C
4
3
TA = -40°C
TA = +85°C
2
1
0
1500 1600 1700 1800 1900 2000 2100 2200
OPERATING FREQUENCY (MHz)
OUTPUT POWER (dBm)
5
MAX9988 toc07
6
MAX9988 toc08
18.0
17.8
17.6
17.4
17.2
17.0
16.8
16.6
16.4
16.2
16.0
15.8
15.6
15.4
15.2
15.0
POUT
ICC
-40
-20
0
20
40
60
AMBIENT TEMPERATURE (°C)
80
OUTPUT POWER vs. SUPPLY VOLTAGE
190
188
186
184
182
180
178
176
174
172
170
168
166
164
162
160
MAX9988 toc09
18.0
OUT1, OUT2 OUTPUT POWER (dBm)
0
SUPPLY CURRENT (mA)
-2
TA = +85°C
14
12
-4
TA = +25°C
15
-3
-6
TA = -40°C
19
OUTPUT POWER (dBm)
2
TA = -40°C
19
OUTPUT POWER (dBm)
3
INPUT POWER (dBm)
20
MAX9988 toc04
TA = +25°C AND +85°C
1
-5 -4 -3 -2 -1 0 1 2 3 4 5 6 7 8 9 10
INPUT POWER (dBm)
5
4
10
-5 -4 -3 -2 -1 0 1 2 3 4 5 6 7 8 9 10
20
MAX9988 toc05
5
TA = +85°C
14
140
0
TA = +25°C
15
12
-5
MAX9988 toc03
16
11
-10
TA = -40°C
17
12
OUTPUT POWER (dBm)
OUTPUT POWER (dBm)
18
TA = +25°C
17
145
-15
OUTPUT POWER (dBm)
19
6.0
17.5
OUT2
5.5
17.0
OUT1
5.0
4.5
16.5
16.0
4.0
OUTPLL
15.5
3.5
15.0
3.0
14.5
2.5
14.0
2.0
4.5 4.6 4.7 4.8 4.9 5.0 5.1 5.2 5.3 5.4 5.5
SUPPLY VOLTAGE (V)
_______________________________________________________________________________________
7
PLL OUTPUT POWER (dBm)
165
TA = -40°C
18
OUTPUT POWER (dBm)
170
19
OUTPUT POWER (dBm)
TA = +85°C
OUTPUT POWER vs. INPUT POWER, OUT2
20
MAX9988 toc02
MAX9988 toc01
175
SUPPLY CURRENT (mA)
OUTPUT POWER vs. INPUT POWER, OUT1
20
MAX9988 toc06
SUPPLY CURRENT vs. OUTPUT POWER
180
MAX9987/MAX9988
Typical Operating Characteristics (continued)
(VCC = 5.0V, nominal bias, fIN = 1800MHz, PIN = +7dBm, TA = +25°C, unless otherwise noted.) (Shaded regions are outside the
guaranteed operating range, and are provided for reference only.)
Typical Operating Characteristics (continued)
(VCC = 5.0V, nominal bias, fIN = 1800MHz, PIN = +7dBm, TA = +25°C, unless otherwise noted.) (Shaded regions are outside the
guaranteed operating range, and are provided for reference only.)
MAX9988
SMALL-SIGNAL GAIN vs. FREQUENCY
OUT2
15
14
13
155
OUT1
-18
11
10
150
4.5 4.6 4.7 4.8 4.9 5.0 5.1 5.2 5.3 5.4 5.5
-20
1.5
1.6
1.7
SUPPLY VOLTAGE (V)
OUTPUT RETURN LOSS vs. FREQUENCY
2.1
2.2
1.5
ISOLATION (dB)
ISOLATION (dB)
-40
OUT2 TO IN
-50
-40
-65
1.7
1.8
1.9
2.0
2.1
2.2
1.7
1.8
1.9
2.0
OUT2 TO OUT1
2.1
2.2
1.5
1.6
1.7
-15
PLL TO OUT_
-25
-30
-140
MAX9988 toc16
VCC = 5.0V
TA = +25°C
PIN = +7dBm
1.8
1.9
OUT2 TO PLL
-40
±100MHz OFFSET
-145
-150
-155
OUT1 TO PLL
-50
-160
1.5
1.6
1.7
1.8
1.9
2.0
FREQUENCY (GHz)
2.1
2.2
2.0
FREQUENCY (GHz)
OUTPUT NOISE (dBm/Hz)
ISOLATION (dB)
-45
OUTPUT NOISE vs. INPUT POWER
-35
8
-40
-60
PLL ISOLATION vs. FREQUENCY
-45
-35
FREQUENCY (GHz)
0
-20
OUT1 TO OUT2
-30
-65
1.6
FREQUENCY (GHz)
-10
2.2
-55
OUT1 TO IN
1.5
-5
2.1
VCC = 5.0V
TA = +25°C
PIN = +7dBm
-50
-55
-60
2.0
-25
-35
-35
1.9
-20
PLL TO IN
-45
1.8
OUT TO OUT ISOLATION vs. FREQUENCY
-30
OUT1
1.6
1.7
-15
MAX9988 toc14
-25
-25
1.5
1.6
FREQUENCY (GHz)
VCC = 5.0V
TA = +25°C
PIN = +7dBm
-20
-20
-30
2.0
OUT TO IN ISOLATION vs. FREQUENCY
OUT2
-15
1.9
-15
MAX9988 toc13
VCC = 5.0V
TA = +25°C
PIN = +7dBm
OUTPLL
-10
1.8
FREQUENCY (GHz)
0
-5
-14
-16
12
PLL NOT BIASED
-12
MAX9988 toc15
160
-10
MAX9988 toc17
PLL BIASED
165
VCC = 5.0V
TA = +25°C
PIN = +7dBm
-8
RETURN LOSS (dB)
16
170
-6
MAX9988 toc11
VCC = 5.0V
TA = +25°C
PIN = -15dBm
NORMAL BIAS
17
GAIN (dB)
SUPPLY CURRENT (mA)
175
INPUT RETURN LOSS vs. FREQUENCY
18
MAX9988 toc10
180
MAX09988 toc12
SUPPLY CURRENT
vs. SUPPLY VOLTAGE
RETURN LOSS (dB)
MAX9987/MAX9988
+14dBm to +20dBm LO Buffers/Splitters
with ±1dB Variation
4
5
6
7
8
9
INPUT POWER (dBm)
_______________________________________________________________________________________
10
2.1
2.2
+14dBm to +20dBm LO Buffers/Splitters
with ±1dB Variation
PIN
NAME
FUNCTION
1, 4, 8, 9, 13,
17, 18, EP
GND
2
IN
3
VCCREF
5
REF
6
BIASIN
Bias Connection for Input Buffer. Set compressed power point for input amplifier with a resistor to
REF or GND. For +17dBm output power, no external biasing resistors are required. See Applications
Information section for information.
7
BIASOUT
Bias Connection for Output Amplifiers. Set compressed power point for OUT1 and OUT2 with a
resistor to REF or ground. For +17dBm output power, no external biasing resistors are required. See
Applications Information section for information.
Ground
Input. Internally matched 50Ω RF input. AC couple to this pin.
Supply. Supply connection for on-chip voltage and current references. See Applications Information
for information on decoupling.
Voltage Reference Output. Output for on-chip 1.5V bandgap voltage reference. See
Applications Information section for information on decoupling.
10
OUT2
Output 2. Internally matched 50Ω RF output. AC couple to this pin.
11, 12
VCC3
Supply. Supply connection for OUT2.
14, 15
VCC2
Supply. Supply connection for OUT1.
16
OUT1
Output 1. Internally matched 50Ω RF output. AC couple to this pin.
19
VCC1
Supply. Supply connection for input amplifier.
20
OUTPLL
Output PLL. Output for driving optional external PLL.
Detailed Description
The MAX9987/MAX9988 LO amplifiers/splitters each
consist of a single input amplifier, a two-way passive
power splitter, two separate output amplifiers, as well as
a third buffer amplifier to drive the LO’s PLL. The bias
currents for the amplifiers are adjustable through off-chip
resistors. This allows the output level to be precision set
anywhere from +14dBm to +20dBm. The PLL output is
preset to +3dBm (about 900mVP-P into 50Ω).
Power levels are typically ±1dB over the full supply, input
power, frequency, and temperature range. Precision
power control is achieved by internal control circuitry.
Maintaining tight power control keeps the system engineer from over specifying the LO drive in order to guarantee a linearity specification in the base-station mixer.
More than 40dB isolation between the LO outputs and
the input prevents VCO pulling, and the 30dB outputto-output isolation reduces branch-to-branch coupling.
The MAX9987 is specified from 700MHz to 1100MHz,
and the MAX9988 is specified from 1500MHz to
2200MHz. Both are offered in compact 5mm ✕ 5mm 20pin QFN packages with exposed paddle.
Input Amplifier
A single low-noise input amplifier before the passive
splitter provides gain and isolation. The compressed
output power for this stage is controlled by the bias setting resistors R1 or R4 (see Typical Application Circuit).
These resistors are not required for the nominal +17dBm
output; see Table 1 for bias resistor values to obtain
+14dBm to +20dBm output power.
The input is internally matched to 50Ω, and typical
VSWR is no more than 2:1 over all operating conditions.
Since the input is internally biased, provide a DC block
at the input pin.
PLL Amplifier and Output
A small amount of power is tapped off from the input
amplifier’s output, and fed to a high-isolation buffer to
drive the PLL output at +3dBm. If the PLL output is not
required, it can be disabled by removing R3; disabling
the PLL output saves 12mA supply current.
Passive Two-Way Splitter
The input amplifier drives an integrated power splitter.
All impedance matching between stages is on-chip, so
no external tuning components are required.
_______________________________________________________________________________________
9
MAX9987/MAX9988
Pin Description
MAX9987/MAX9988
+14dBm to +20dBm LO Buffers/Splitters
with ±1dB Variation
Table 1. External Resistor Values for +14dBm to +20dBm Output Power
NOMINAL
OUTPUT POWER
(dBm)
R1 (Ω)
R2 (Ω)
R4 (Ω)
R5 (Ω)
MAX9987
INPUT DRIVE
(dBm)
MAX9988
INPUT DRIVE
(dBm)
+20
1.35k
2.0k
Open
Open
10 ±3
12 ±3
+19
2.2k
3.0k
Open
Open
9 ±3
11 ±3
10 ±3
+18
5.0k
6.0k
Open
Open
8 ±3
+17
Open
Open
Open
Open
7 ±3
9 ±3
+16
Open
Open
1.8k
3.0k
6 ±3
8 ±3
+15
Open
Open
0.9k
1.1k
5 ±3
7 ±3
+14
Open
Open
0.6k
0.6k
4 ±3
6 ±3
Table 2. Component Values for Typical
Application Circuit
COMPONENT VALUE
DESIGNATION
MAX9987
(LOWBAND)
MAX9988
(HIGHBAND)
C1, C6
100nF
100nF
C3
100pF
100nF
C2, C4, C5, C7, C8,
C9, C12, C13, C14
47pF
22pF
C10, C11
5pF
10pF
R1, R2, R4, R5
See Table 1
See Table 1
R3
100Ω
100Ω
Input Drive Level
In the case of the MAX9987, the typical required input
drive level is +7dBm for +17dBm output, or +10dBm for
+20dBm output. The MAX9988 uses slightly higher
input levels (see Table 1). The typical VCO cannot provide sufficient drive by itself; the typical application follows the VCO with attenuation (about +3dB), and then
with a low-noise gain block. This allows the VCO to
drive the MAX9987/MAX9988 input at the required level
without being load-pulled.
Output Drive Level
The output drive of the MAX9987/MAX9988 is nominally
+17dBm ±1dB. This is the typical application, with no
external bias-setting resistors at INBIAS and OUTBIAS.
Output power can be set from +14dBm to +20dBm by
using the bias-setting resistor values listed in Table 1.
Driver Amplifiers and Outputs
Each of the output amplifiers are similar to the input
amplifier, except they are biased higher to provide more
output power. For example, with an input power of
+10dBm, the MAX9987 can deliver +20dBm at both outputs. The bias is adjustable; see Table 1 for details.
Both RF outputs are internally matched to 50Ω, with a
typical VSWR limit of 2:1. Provide DC blocking capacitors
at the outputs.
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 inductance. For best performance, route the ground pin
traces directly to the exposed pad underneath the
package. This pad must 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 pad on the bottom of the device
package to a PC board exposed pad.
Input and Output Matching
All input and output matching is accomplished on-chip;
no external matching circuitry is required. Use a DC
block of about 47pF (lowband) or 22pF (highband) at the
input and the outputs. Because these parts are internally
broadband matched, adjusting external component
values can optimize performance for a particular band.
10
Chip Information
TRANSISTOR COUNT: 89
PROCESS: BiCMOS
______________________________________________________________________________________
+14dBm to +20dBm LO Buffers/Splitters
with ±1dB Variation
5.0V
5.0V
C1
C2
C3
MAX9987
MAX9988
C4
TO OUTPUT 1
C13
C14
20
GND
19
18
17
OUT1
GND
GND
OUT TO PLL
(+3dBm)
VCC1
OUTPLL
R3
100Ω
EXPOSED PAD
1
5.0V
16
15
VCC2
C11
INPUT FROM LO
IN
2
14
3
13
4
12
C12
VCC2
C5
VCCREF
5.0V
C6
GND
C7
GND
REF
BIAS
11
5
VCC3
5.0V
VCC3
C10
R4*
OUT2
10
9
GND
8
BIASOUT
BIASIN
7
GND
6
C9
TO OUTPUT 2
R5*
C8
R1*
R2*
* FOR THESE VALUES, SEE TABLE 1.
FOR CAPACITOR VALUES, SEE TABLE 2.
______________________________________________________________________________________
11
MAX9987/MAX9988
Typical Application Circuit/Pin Configuration
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.)
32L QFN.EPS
MAX9987/MAX9988
+14dBm to +20dBm LO Buffers/Splitters
with ±1dB Variation
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.
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Printed USA
is a registered trademark of Maxim Integrated Products.