MAX9987 Datasheet, PDF (1/12 Pages) Maxim Integrated Products – +14dBm to +20dBm LO Buffers/Splitters with ±1dB Variation

19-2416; Rev 0; 4/02
+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 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.
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
output-to-output port isolation, and are offered in 5mm ✕
5mm 20-pin QFN packages with exposed paddle.
Applications
Cellular/GSM/DCS/PCS/UMTS Base Station
Tx/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
o ±1dB Output Power Variation
o +14dBm to +20dBm Adjustable Output Power
o Two-Way Power Splitting
o 40dB Reverse Isolation
o More than 30dB Output-to-Output Isolation
o Low Output Noise: -170dBc/Hz at +17dBm
o 160mA Supply Current at +17dBm
o ESD Protection
o Isolated PLL Output (+3dBm)
Ordering Information
PART
TEMP
RANGE
PIN-
FREQUENCY
PACKAGE
RANGE
MAX9987EGP -40°C to 85°C 20 QFN-EP*
700MHz to
1100MHz
MAX9988EGP -40°C to 85°C 20 QFN-EP*
*EP = Exposed paddle
1500MHz to
2200MHz
TO PLL
PRESCALER
RF LO
Typical Operating Circuit and Block Diagram
OUTPLL
(+3dBm)
PLL BUFFER
MAX9987
MAX9988
OUTPUT AMP
(1)
OUT1
(+17dBm)
IN
(+7dBm)
INPUT AMP
PASSIVE TWO-WAY
POWER SPLITTER
BIAS
BIASIN
BIASOUT
BIAS
CONTROL
NETWORK
OUTPUT AMP
(2)
OUT2
(+17dBm)
RF INPUT
(1)
IF OUTPUT
(1)
RF INPUT
(2)
IF OUTPUT
(2)
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