L-Band Tuner with Programmable Baseband Filter

The MAX2121B low-cost, direct-conversion tuner IC is designed for satellite set-top and VSAT applications.

The device directly converts the satellite signals from the LNB to baseband using a broadband I/Q downconverter. The operating frequency range extends from 925MHz to 2250MHz.

The device includes an LNA and an RF variable-gain amplifier, I and Q downconverting mixers, and digitally controlled baseband filters (40MHz to 124MHz) and variable-gain amplifiers. Together, the RF and baseband variable-gain amplifiers provide more than 80dB of gain control range.

The device 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 device is the most advanced broadband/VSAT DBS tuner available. The low noise figure eliminates the need for an external LNA. A small number of passive components are needed to form a complete broadband satellite tuner DVB-S2 RF front-end solution. The tuner is available in a very small, 5mm x 5mm, 28-pin TQFN package.

Applications

* DBS Tuner * Navigation Systems * Satellite Set-Top Box * VSATs

* Monolithic Receiver Saves Cost and Space

* Integrated VCO with Low Phase Noise: -97dBc/Hz at 10kHz

* Integrated 14-Bit Fractional-N Synthesizer

* Address Pin Allows for Multi-Tuner Applications

* Low Power Reduces Cost

* 495mW Power Dissipation

* 10mW Standby Mode

* High Dynamic Range Eliminates Need for External LNA and/or Attenuators

* -75dBm to 0dBm Input Power

* 8dB Noise Figure

* Integrated LP Filters Simplify Design

* Programmable Bandwidth from 40MHz to 124MHz

* Differential I/Q Interface Minimizes EMI

* 1VP-P Full-Scale Outputs

* Serial Interface and Small Package Reduce Size

* 5mm x 5mm, 28-Pin TQFN Package

* I²C 2-Wire Serial Interface