The MAX2117 low-cost, direct-conversion tuner is intended for receiving MMDS transmissions in the 470MHz to 1000MHz band. The MAX2117 is designed to be used in consumer set-top boxes and is compatible with most DVB-S demodulators.
The MAX2117 directly converts the QPSK broadcast signals from the antenna to baseband using a broadband I/Q downconverter. The tuner provides differential I and Q outputs to the demodulator IC.
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 QPSK demodulators.
The MAX2117 includes fully monolithic VCOs, as well as a complete 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 MAX2117 is the most advanced MMDS 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 MMDS front-end solution. The tuner is available in a very small 28-pin thin QFN package.
