MAX2112.pdf

The MAX2112 low-cost, direct-conversion tuner IC is
designed for satellite set-top and VSAT applications
The IC is intended for 8PSK and Digital Video
Broadcast (DVB-S2) applications.
The MAX2112 directly converts the satellite signals
from the LNB to baseband using a broadband I/Q
downconverter. The operating frequency range extends
from 925MHz to 2175MHz.
The device includes an LNA and an RF variable-gain
amplifier, I and Q downconverting mixers, and baseband
lowpass filters with programmable cutoff frequency contro
and digitally controlled baseband variable-gain amplifiers
Together, the RF and baseband variable-gain amplifiers
provide more than 80dB of gain control range. The IC is
compatible with virtually all DVB-S2 demodulators.
The MAX2112 includes fully monolithic VCOs, as well as
a complete fractional-N frequency synthesizer
Additionally, an on-chip crystal oscillator is provided
along with a buffered output for driving additional tuners
and demodulators. Synthesizer programming and device
configuration are accomplished with a 2-wire serial inter-
face. The IC features a VCO autoselect (VAS) function
that automatically selects the proper VCO. For multituner
applications, the device can be configured to have one
of two 2-wire interface addresses. A low-power standby
mode is available whereupon the signal path is shu
down while leaving the reference oscillator, digital inter-
face, and buffer circuits active, providing a method to
reduce power in single and multituner applications.
The MAX2112 is the most advanced DBS tuner avail-
able today. The low noise figure eliminates the need for
an external LNA. A small number of passive compo-
nents are needed to form a complete DVB-S2 RF front-
end solution. The tuner is available in a very smal
28-pin thin QFN package.