Complete, Direct-Conversion Tuner for DVB-S2 Applications

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 interface, and buffer circuits active, providing a method to reduce power in single and multituner applications.

The MAX2112 is the most advanced DBS tuner available today. The low noise figure eliminates the need for an external LNA. A small number of passive components are needed to form a complete DVB-S2 RF front-end solution. The tuner is available in a very small 28-pin thin QFN package.

Applications

* DirecTV and Dish Network DBS * DVB-S2 * VSATs

* 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