General Description

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 control 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 interface. 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 shut down while leaving the reference oscillator, digital inter face, and buffer circuits active, providing a method to reduce power in single and multituner applications.

特性 Features

? 925MHz to 2175MHz Frequency Range

? Monolithic VCO

?? Low Phase Noise: -97dBc/Hz at 10kHz

?? No Calibration Required

? High Dynamic Range: -75dBm to 0dBm

? Integrated Variable BW LP Filters: 4MHz to 40MHz

? Single +3.3V ±5 Supply

? Low-Power Standby Mode

? Address Pin for Multituner Applications

? Differential I/Q Interface

? I2C 2-Wire Serial Interface

? Very Small 28-Pin TQFN Package

Applications

?? DirecTV and Dish Network DBS

?? DVB-S2

?? VSATs