19-2416; Rev 1; 10/02
+14dBm to +20dBm LO Buffers/Splitters
with 1dB ꢀariation
General Description
Features
The MAX9987 and MAX9988 LO buffers/splitters each
integrate a passive two-way power splitter with high-
isolation 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 OutOuBꢀPoweBꢁVerVurPꢂ
ꢀ +±41dmBuPB+201dmBA1jOsuVblwB OutOuBꢀPowe
ꢀ ToP-WVyBꢀPoweBStlruurꢂg
ꢀ 401dBRwvweswBIsPlVurPꢂ
ꢀ MPewBuhVꢂB301dB OutOu-uP- OutOuBIsPlVurPꢂ
ꢀ LPoB OutOuBNPrsw:B-±701dc/HzBVuB+±71dm
ꢀ ±60mABSOttlyBCOeewꢂuBVuB+±71dm
ꢀ ESDBꢀePuwcurPꢂ
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 30dB
ꢀ IsPlVuw1BꢀLLB OutOuB(+31dm)
✕
output-to-output port isolation, and are offered in 5mm
5mm 20-pin QFN packages with exposed paddle.
Applications
Ordering Information
Cellular/GSM/DCS/PCS/UMTS Base Station
Tx/Rx LO Drive
TEMꢀ
RANGE
ꢀIN-
ꢀACKAGE
FREQUENCY
RANGE
ꢀART
Base Station Main and Diversity Channels
Coherent Receivers
700MHz to
1100MHz
MAX9987EGP -40°C to 85°C 20 QFN-EP*
ISM Wireless LAN
1500MHz to
2200MHz
MAX9988EGP -40°C to 85°C 20 QFN-EP*
*EP = Exposed paddle.
Wireless Local Loop
Local Multipoint Distribution Service
Point-to-Point Systems
Typical Operating Circuit and Block Diagram
RF INPUT
(1)
OUTPUT AMP
(1)
PLL BUFFER
MAX9987
MAX9988
OUTPLL
(+3dBm)
TO PLL
PRESCALER
OUT1
(+17dBm)
IF OUTPUT
(1)
IN
(+7dBm)
RF INPUT
(2)
INPUT AMP
RF LO
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.