+14dBm to +20dBm LO Buffers/Splitters with ±1dB Variation · General Description The MAX9987 and MAX9988 LO buffers/splitters each integrate a passive two-way power splitter with

General DescriptionThe MAX9987 and MAX9988 LO buffers/splitters eachintegrate a passive two-way power splitter with high-isolation input and output buffer amplifiers. Thesebuffers are designed to provide the high output(+14dBm to +20dBm) necessary to drive the LO inputsof high-linearity passive mixers, while offering 40dBreverse isolation to prevent LO pulling. The MAX9987 isinternally matched for the cellular/GSM bands, and theMAX9988 is matched for the DCS/PCS/UMTS bands.

The typical application circuit provides a nominal+17dBm output power with ±1dB variation over supply,temperature, and input power. With two optional resis-tors, the output power can be precision set from+14dBm to +20dBm. The devices offer more than 30dBoutput-to-output port isolation, and are offered in 5mm 5mm 20-pin thin QFN packages with exposed paddle.

ApplicationsCellular/GSM/DCS/PCS/UMTS Base StationTx/Rx LO Drive

Base Station Main and Diversity Channels

Coherent Receivers

ISM Wireless LAN

Wireless Local Loop

Local Multipoint Distribution Service

Point-to-Point Systems

Features♦ ±1dB Output Power Variation

♦ +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

♦ 160mA Supply Current at +17dBm

♦ Isolated PLL Output (+3dBm)

MA

X9

98

7/M

AX

99

88

+14dBm to +20dBm LO Buffers/Splitterswith ±1dB Variation

________________________________________________________________ Maxim Integrated Products 1

MAX9987MAX9988

BIAS

BIASIN

RF LO

TO PLL PRESCALER

PLL BUFFER

INPUT AMP

OUTPUT AMP(2)

OUTPUT AMP(1)

RF INPUT(1)

IF OUTPUT(1)

PASSIVE TWO-WAYPOWER SPLITTER

IN(+7dBm)

OUTPLL(+3dBm)

OUT1(+17dBm)

OUT2(+17dBm)

BIASOUT

BIAS CONTROLNETWORK

RF INPUT(2)

IF OUTPUT(2)

Typical Operating Circuit and Block Diagram

Ordering Information

19-2416; Rev 2; 3/04

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.

PARTTEMP

RANGEPIN-PACKAGE

FREQUENCYRANGE

MAX9987ETP-T -40°C to 85°C 20 ThinQFN-EP*

700MHz to1100MHz

MAX9988ETP-T -40°C to 85°C 20 ThinQFN-EP*

1500MHz to2200MHz

*EP = Exposed paddle.

MA

X9

98

7/M

AX

99

88


2 _______________________________________________________________________________________

ABSOLUTE MAXIMUM RATINGS

Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functionaloperation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure toabsolute maximum rating conditions for extended periods may affect device reliability.

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 5mAINBIAS, OUTBIAS, to GND..................................-0.3V to +0.75VPLLBIAS ......................................................................Sink 25mARF 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/WJunction Temperature ......................................................+150°COperating Temperature Range ...........................-40°C to +85°CStorage Temperature Range .............................-65°C to +150°CLead Temperature (soldering, 10s) .................................+300°C

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 specificationsare for VCC = 5.0V and TA = +25°C.) (Note 1)

PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS

Supply Voltage VCC 4.75 5.00 5.25 V

Low power setting(see Table 1 for resistor values)

110

Nominal power setting(R1, R2, R4, and R5 not installed)

139 155 171Supply Current ICC

High power setting(see Table 1 for resistor values)

221

mA

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 specificationsare for VCC = 5.0V and TA = +25°C.) (Note 1)


Supply Voltage VCC 4.75 5.00 5.25 V

Low power setting(see Table 1 for resistor values)

120

Nominal power setting(R1, R2, R4, and R5 not installed)

150 162 175Supply Current ICC

High power setting(see Table 1 for resistor values)

229

mA

MA

X9

98

7/M

AX

99

88


_______________________________________________________________________________________ 3

AC ELECTRICAL CHARACTERISTICS—MAX9987(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 SYMBOL CONDITIONS MIN TYP MAX UNITSOperating Frequency f 700 1100 MHz

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

Output Power (Main Drivers) POUTLO

High power setting, PIN = +10dBm(see Table 1 for resistor values)

19.7

dBm

Output Power (PLL Driver) POUTPLL 3.7 dBm

Input VSWR VSWRIN 1.2:1

Output VSWR VSWROUT 1.7:1

Output-Noise Power Density PNOISEVCC = 5.0V, ±100MHz offset(R1, R2, R4, and R5 not installed)

-152 dBm/Hz

OUT1 to OUT2 Isolation S23VCC = 5.0V, nominal power setting(R1, R2, R4, and R5 not installed)

45 dB


39 dB

OUT1 to RFIN Isolation S12VCC = 5.0V, nominal power setting(R1, R2, R4, and R5 not installed)

48 dB


50 dB

MA

X9

98

7/M

AX

99

88


4 _______________________________________________________________________________________


Operating Frequency f 1500 2200 MHz

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

Output Power(Main Drivers)

POUTLO

High power setting, PIN = +12dBm(see Table 1 for resistor values)

19.5

dBm

Output Power(PLL Driver)

POUTPLL 3.6 dBm

Input VSWR VSWRIN 1.5:1

Output VSWR VSWROUT 1.4:1

Output-Noise Power Density PNOISE VCC = 5.0V, ±100MHz offset -152 dBm/Hz


33 dB


44 dB


49 dB


47 dB

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)

Note 1: Devices are 100% DC screened and AC production tested for functionality. Data sheet typical specifications are derivedfrom the average of 30 units from a typical lot, and are tested under the conditions specified for the typical specifications.

MA

X9

98

7/M

AX

99

88


_______________________________________________________________________________________ 5

SUPPLY CURRENT vs. OUTPUT POWEROUTMAIN

MAX

9987

toc0

1

OUTPUT POWER (dBm)

SUPP

LY C

URRE

NT (m

A)

20151050-5-10

145

150

155

160

165

170

180

140-15

175

TA = -40°C

TA = +25°C AND +85°C

OUTPUT POWER vs. INPUT POWEROUT1

MAX9987 toc02

INPUT POWER (dBm)

OUTP

UT P

OWER

(dBm

)

92 3-3-4

11

12

13

14

15

16

17

18

19

20

10-5 1087-2 -1 0 1 4 5 6

TA = +85°C

TA = +25°C

TA = -40°C

OUTPUT POWER vs. INPUT POWEROUT2

MAX9987 toc03

INPUT POWER (dBm)

OUTP

UT P

OWER

(dBm

)

92 3-3-4

11

12

13

14

15

16

17

18

19

20

10-5 1087-2 -1 0 1 4 5 6

TA = +85°C

TA = +25°C

TA = -40°C

OUTPUT POWER vs. INPUT POWER, OUTPLL

MAX

9987

toc0

4

INPUT POWER (dBm)

OUTP

UT P

OWER

(dBm

)

862 4-2 0-4

-4

-3

-2

-1

0

1

2

3

4

5

-5-6 10

TA = +85°C

TA = +25°C

TA = -40°C

OUTPUT POWER vs. FREQUENCY, OUT1

MAX

9987

toc0

5

OPERATING FREQUENCY (MHz)

OUTP

UT P

OWER

(dB

m)

1200800700600

15

16

17

18

20

14500

19

900 1000 1100

TA = +85°C

TA = +25°C TA = -40°C


MAX

9987

toc0

6


OUTP

UT P

OWER

(dBm

)

1200800700600

15

16

17

18

20

14500

19

900 1000 1100

TA = +85°C

TA = +25°C TA = -40°C

OUTPUT POWER vs. FREQUENCY, PLL

MAX

9987

toc0

7


OUTP

UT P

OWER

(dBm

)

1200800700600

1

2

3

4

6

0500

5

900 1000 1100

TA = +85°CTA = +25°C

TA = -40°C

OUTPUT POWER AND SUPPLY CURRENTvs. TEMPERATURE

MAX9987 toc08

AMBIENT TEMPERATURE (°C)

OUTP

UT P

OWER

(dBm

)

806020 400-20

16.2

16.4

16.6

16.8

17.0

17.2

17.4

17.6

17.8

18.0

16.0-40

ICC

160.2

160.4

160.6

160.8

161.0

161.2

161.4

161.6

161.8

162.0

160.0

SUPP

LY C

URRE

NT (m

A)

POUT

OUTPUT POWER vs. SUPPLY VOLTAGEMAX9987 toc09

SUPPLY VOLTAGE (V)

OUT1

, OUT

2 OU

TPUT

POW

ER (

dBm

)

5.54.94.84.74.6

14.5

15.0

15.5

16.0

16.5

17.0

18.0

14.04.5

17.5 OUT2

5.0 5.1 5.2 5.3 5.4

2.5

3.0

3.5

4.0

4.5

5.0

6.0

2.0

5.5

OUT1

OUTPLL

PLL

OUTP

UT P

OWER

(dB

m)

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.)

MAX9987

MA

X9

98

7/M

AX

99

88


6 _______________________________________________________________________________________

Typical Operating Characteristics (continued)(VCC = 5.0V, nominal bias, fIN = 900MHz, PIN = +7dBm, TA = +25°C, unless otherwise noted.) (Shaded regions are outside theguaranteed operating range, and are provided for reference only.)

SUPPLY CURRENT vs. SUPPLY VOLTAGEM

AX99

87 to

c10

SUPPLY VOLTAGE (V)

SUPP

LY C

URRE

NT (

mA)

5.54.94.84.74.6

145

150

155

160

170

1404.5

165

5.0 5.1 5.2 5.3 5.4

PLL NOT BIASED

PLL BIASED

SMALL-SIGNAL GAIN vs. FREQUENCY

MAX

9987

toc1

1

FREQUENCY (GHz)

GAIN

(dB)

1.00.90.80.70.6

14

15

16

17

18

19

130.5 1.1

VCC = 5.0V TA = +25°CPIN = -15dBmNOMINAL BIAS

OUT1

OUT2

INPUT RETURN LOSS vs. FREQUENCY

MAX

9987

toc1

2

FREQUENCY (GHz)

RETU

RN L

OSS

(dB)

1.11.00.90.80.70.6

-35

-30

-25

-20

-15

-10

0

-400.5

-5VCC = 5.0V TA = +25°CPIN = +7dBm

OUTPUT RETURN LOSS vs. FREQUENCY

MAX

9987

toc1

3

FREQUENCY (GHz)

RETU

RN L

OSS

(dB)

1.11.00.90.80.70.6

-18

-16

-14

-12

-10

-8

-4

-200.5

-6

VCC = 5.0V TA = +25°CPIN = +7dBm

-2

0

OUT2

OUT1

PLL

IN ISOLATION vs. FREQUENCYM

AX99

87 to

c14

FREQUENCY (GHz)

ISOL

ATIO

N (d

B)

1.11.00.90.80.70.6

-65

-60

-55

-50

-45

-40

-30

-700.5

-35


-25

-20

OUT2 TO IN

PLL TO IN

OUT1 TO IN

OUT1 AND OUT2 ISOLATION vs. FREQUENCY

MAX

9987

toc1

5

FREQUENCY (GHz)

ISOL

ATIO

N (d

B)

1.11.00.90.80.70.6

-65

-60

-55

-50

-45

-40

-30

-700.5

-35


-25

-20

OUT1 TO OUT2

OUT2 TO OUT1

PLL ISOLATION vs. FREQUENCY

MAX

9987

toc1

6

FREQUENCY (GHz)

ISOL

ATIO

N (d

B)

1.11.00.90.80.70.6

-65

-60

-55

-50

-45

-40

-30

-700.5

-35


-25

-20

OUT2 TO PLL

OUT1 TO PLL

PLL TO OUT_

OUTPUT NOISE POWERvs. INPUT POWER

MAX

9987

toc1

7

INPUT POWER (dBm)

NOIS

E PO

WER

(dBm

/Hz)

98765

-155

-150

-145

-140

-1604 10

±100MHz OFFSET

MAX9987

MA

X9

98

7/M

AX

99

88


_______________________________________________________________________________________ 7

140

150

145

160

155

175

170

165

180

-15 -5-10 0 5 10 15 20

SUPPLY CURRENT vs. OUTPUT POWERM

AX99

88 to

c01

OUTPUT POWER (dBm)

SUPP

LY C

URRE

NT (m

A)

TA = +25°C

TA = +85°C

TA = -40°C

OUTPUT POWER vs. INPUT POWER, OUT1

MAX

9988

toc0

2INPUT POWER (dBm)

OUTP

UT P

OWER

(dBm

)

875 6-2 -1 0 1 2 3 4-4 -3

11

12

13

14

15

16

17

18

19

20

10-5 9 10

TA = -40°C

TA = +85°C

TA = +25°C

OUTPUT POWER vs. INPUT POWER, OUT2

MAX

9988

toc0

3

INPUT POWER (dBm)

OUTP

UT P

OWER

(dBm

)

875 6-2 -1 0 1 2 3 4-4 -3

11

12

13

14

15

16

17

18

19

20

10-5 9 10

TA = -40°C

TA = +25°C

TA = +85°C

-5

-3

-4

-1

-2

1

0

2

4

3

5

-6 -2 0-4 2 4 6 8 10

OUTPUT POWER vs. INPUT POWER, OUTPLL

MAX

9988

toc0

4

INPUT POWER (dBm)

OUTP

UT P

OWER

(dBm

)

TA = +25°C AND +85°C

TA = -40°C

10

13

12

11

15

14

19

18

17

16

20

1500 1600 1700 1800 1900 2000 2100 2200


MAX

9988

toc0

5


OUTP

UT P

OWER

(dBm

)

TA = +85°CTA = +25°C

TA = -40°C

10

13

12

11

15

14

19

18

17

16

20

1500 1600 1700 1800 1900 2000 2100 2200


MAX

9988

toc0

6


OUTP

UT P

OWER

(dBm

)

TA = +85°CTA = +25°C

TA = -40°C

0

2

1

4

3

5

6

1500 1800 19001600 1700 2000 2100 2200

OUTPUT POWER vs. FREQUENCY, OUTPLL

MAX

9988

toc0

7


OUTP

UT P

OWER

(dBm

)

TA = +85°C

TA = +25°C

TA = -40°C

15.0

16.416.216.015.815.615.415.2

16.816.6

17.217.0

17.4

17.817.6

18.0

OUTPUT POWER AND SUPPLY CURRENTvs. TEMPERATURE

MAX9988 toc08

AMBIENT TEMPERATURE (°C)

OUTP

UT P

OWER

(dBm

)

-40 0 20-20 40 60 80160

174172170168166164162

178176

182180

184

188186

190

SUPP

LY C

URRE

NT (m

A)

ICC

POUT

14.0

15.0

14.5

15.5

17.0

17.5

16.5

16.0

18.0

4.5 4.7 4.8 4.9 5.04.6 5.1 5.2 5.3 5.4 5.5

OUTPUT POWER vs. SUPPLY VOLTAGEMAX9988 toc09

SUPPLY VOLTAGE (V)

OUT1

, OUT

2 OU

TPUT

POW

ER (d

Bm)

2.0

3.0

2.5

3.5

5.0

5.5

4.5

4.0

6.0PL

L OU

TPUT

POW

ER (d

Bm)

OUT2

OUT1

OUTPLL

_______________________________________________________________________________________ 7


MAX9988

MA

X9

98

7/M

AX

99

88


8 _______________________________________________________________________________________

150

165

160

155

170

175

180

4.5 4.94.84.6 4.7 5.0 5.1 5.2 5.3 5.4 5.5

SUPPLY CURRENTvs. SUPPLY VOLTAGE

MAX

9988

toc1

0

SUPPLY VOLTAGE (V)

SUPP

LY C

URRE

NT (m

A)

PLL BIASED

PLL NOT BIASED

10

12

11

14

13

17

16

15

18

1.5 1.71.6 1.8 1.9 2.0 2.1 2.2

SMALL-SIGNAL GAIN vs. FREQUENCY

MAX

9988

toc1

1

FREQUENCY (GHz)

GAIN

(dB)

VCC = 5.0VTA = +25°CPIN = -15dBmNORMAL BIASOUT2

OUT1

-20

-16

-18

-12

-14

-8

-10

-6

1.5 1.7 1.81.6 1.9 2.0 2.1 2.2

INPUT RETURN LOSS vs. FREQUENCY

MAX

0998

8 to

c12

FREQUENCY (GHz)

RETU

RN L

OSS

(dB)

VCC = 5.0VTA = +25°CPIN = +7dBm

-40

-30

-35

-20

-25

-5

-10

-15

0

1.5 1.71.6 1.8 1.9 2.0 2.1 2.2

OUTPUT RETURN LOSS vs. FREQUENCY

MAX

9988

toc1

3

FREQUENCY (GHz)

RETU

RN L

OSS

(dB)


OUT2

OUT1

OUTPLL

-65

-50

-55

-60

-40

-45

-20

-25

-30

-35

-15

1.5 1.6 1.7 1.8 1.9 2.0 2.1 2.2

OUT TO IN ISOLATION vs. FREQUENCY

MAX

9988

toc1

4

FREQUENCY (GHz)

ISOL

ATIO

N (d

B)


OUT1 TO IN

OUT2 TO IN

PLL TO IN

-65

-50

-55

-60

-40

-45

-20

-25

-30

-35

-15

1.5 1.6 1.7 1.8 1.9 2.0 2.1 2.2

OUT TO OUT ISOLATION vs. FREQUENCY

MAX

9988

toc1

5FREQUENCY (GHz)

ISOL

ATIO

N (d

B)


OUT1 TO OUT2

OUT2 TO OUT1

-50

-35

-40

-45

-25

-30

-5

-10

-15

-20

0

1.5 1.6 1.7 1.8 1.9 2.0 2.1 2.2

PLL ISOLATION vs. FREQUENCY

MAX

9988

toc1

6

FREQUENCY (GHz)

ISOL

ATIO

N (d

B)


OUT2 TO PLL

PLL TO OUT_

OUT1 TO PLL

-140

-145

-150

-155

-1604 75 6 8 9 10

OUTPUT NOISE vs. INPUT POWER

MAX

9988

toc1

7

INPUT POWER (dBm)

OUTP

UT N

OISE

(dBm

/Hz)

±100MHz OFFSET


MAX9988

MA

X9

98

7/M

AX

99

88


_______________________________________________________________________________________ 9

Detailed DescriptionThe MAX9987/MAX9988 LO amplifiers/splitters eachconsist of a single input amplifier, a two-way passivepower splitter, two separate output amplifiers, as well asa third buffer amplifier to drive the LO’s PLL. The biascurrents for the amplifiers are adjustable through off-chipresistors. This allows the output level to be precision setanywhere from +14dBm to +20dBm. The PLL output ispreset to +3dBm (about 900mVP-P into 50Ω).

Power levels are typically ±1dB over the full supply, inputpower, frequency, and temperature range. Precisionpower control is achieved by internal control circuitry.Maintaining tight power control keeps the system engi-neer from over specifying the LO drive in order to guar-antee a linearity specification in the base-station mixer.

More than 40dB isolation between the LO outputs andthe input prevents VCO pulling, and the 30dB output-to-output isolation reduces branch-to-branch coupling.

The MAX9987 is specified from 700MHz to 1100MHz,and the MAX9988 is specified from 1500MHz to2200MHz. Both are offered in compact 5mm 5mm 20-pin QFN packages with exposed paddle.

Input AmplifierA single low-noise input amplifier before the passivesplitter provides gain and isolation. The compressedoutput power for this stage is controlled by the bias set-ting resistors R1 or R4 (see Typical Application Circuit).These resistors are not required for the nominal +17dBmoutput; see Table 1 for bias resistor values to obtain+14dBm to +20dBm output power.

The input is internally matched to 50Ω, and typicalVSWR is no more than 2:1 over all operating conditions.Since the input is internally biased, provide a DC blockat the input pin.

PLL Amplifier and OutputA small amount of power is tapped off from the inputamplifier’s output, and fed to a high-isolation buffer todrive the PLL output at +3dBm. If the PLL output is notrequired, it can be disabled by removing R3; disablingthe PLL output saves 12mA supply current.

Passive Two-Way SplitterThe input amplifier drives an integrated power splitter.All impedance matching between stages is on-chip, sono external tuning components are required.

Pin Description

PIN NAME FUNCTION

1, 4, 8, 9, 13,17, 18, EP

GND Ground

2 IN Input. Internally matched 50Ω RF input. AC couple to this pin.

3 VCCREFSupply. Supply connection for on-chip voltage and current references. See Applications Informationfor information on decoupling.

5 REFVoltage Reference Output. Output for on-chip 1.5V bandgap voltage reference. SeeApplications Information section for information on decoupling.

6 BIASINBias Connection for Input Buffer. Set compressed power point for input amplifier with a resistor toREF or GND. For +17dBm output power, no external biasing resistors are required. See ApplicationsInformation section for information.

7 BIASOUTBias Connection for Output Amplifiers. Set compressed power point for OUT1 and OUT2 with aresistor to REF or ground. For +17dBm output power, no external biasing resistors are required. SeeApplications Information section for information.

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.

MA

X9

98

7/M

AX

99

88


10 ______________________________________________________________________________________

Driver Amplifiers and OutputsEach of the output amplifiers are similar to the inputamplifier, except they are biased higher to provide moreoutput power. For example, with an input power of+10dBm, the MAX9987 can deliver +20dBm at both out-puts. 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 capacitorsat the outputs.

Applications InformationInput and Output Matching

All input and output matching is accomplished on-chip;no external matching circuitry is required. Use a DCblock of about 47pF (lowband) or 22pF (highband) at theinput and the outputs. Because these parts are internallybroadband matched, adjusting external component values can optimize performance for a particular band.

Input Drive LevelIn the case of the MAX9987, the typical required inputdrive level is +7dBm for +17dBm output, or +10dBm for+20dBm output. The MAX9988 uses slightly higherinput levels (see Table 1). The typical VCO cannot pro-vide sufficient drive by itself; the typical application fol-lows the VCO with attenuation (about +3dB), and thenwith a low-noise gain block. This allows the VCO todrive the MAX9987/MAX9988 input at the required levelwithout being load-pulled.

Output Drive LevelThe output drive of the MAX9987/MAX9988 is nominally+17dBm ±1dB. This is the typical application, with noexternal bias-setting resistors at INBIAS and OUTBIAS.Output power can be set from +14dBm to +20dBm byusing the bias-setting resistor values listed in Table 1.

Layout ConsiderationsA properly designed PC board is an essential part ofany RF/microwave circuit. Keep RF signal lines as shortas possible to reduce losses, radiation, and induc-tance. For best performance, route the ground pintraces directly to the exposed pad underneath thepackage. This pad must be connected to the groundplane of the board by using multiple vias under thedevice to provide the best RF/thermal conduction path.Solder the exposed pad on the bottom of the devicepackage to a PC board exposed pad.

Chip InformationTRANSISTOR COUNT: 89

PROCESS: BiCMOS

Table 1. External Resistor Values for +14dBm to +20dBm Output Power

NOMINALOUTPUT POWER

(dBm)R1 (Ω) R2 (Ω) R4 (Ω) R5 (Ω)

MAX9987INPUT DRIVE

(dBm)

MAX9988INPUT DRIVE

(dBm)

+20 1.35k 2.0k Open Open 10 ±3 12 ±3

+19 2.2k 3.0k Open Open 9 ±3 11 ±3

+18 5.0k 6.0k Open Open 8 ±3 10 ±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 TypicalApplication 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

MA

X9

98

7/M

AX

99

88


______________________________________________________________________________________ 11

MAX9987MAX9988

1

2

3

4

5

6 7 8 9 10

20 19 18 17 16

15

14

13

12

11BIAS

R4* R5*

GND

BIAS

OUT

BIAS

IN

GND

GND

VCC1

OUTP

LL

GND

OUT2

OUT1

R2*

C8

C13

C10

VCC3

VCC3

VCC2

VCC2

GND

GND

IN

VCCREF

GND

REF

C9

5.0V

C1

R3100Ω

C2

C6 C7

C14

C5

OUT TO PLL(+3dBm)

INPUT FROM LO

5.0V

5.0V

5.0V

TO OUTPUT 2

TO OUTPUT 1

R1*

C11 C12

C3 C4

5.0V

* FOR THESE VALUES, SEE TABLE 1. FOR CAPACITOR VALUES, SEE TABLE 2.

EXPOSED PAD

Typical Application Circuit/Pin Configuration

MA

X9

98

7/M

AX

99

88


Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses areimplied. Maxim reserves the right to change the circuitry and specifications without notice at any time.

12 ____________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600

© 2004 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products.

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

.EP

S

Documents

+14dBm to +20dBm LO Buffers/Splitters with ±1dB Variation · General Description The MAX9987 and MAX9988 LO buffers/splitters each integrate a passive two-way power splitter with