The MAX2223 low-cost, direct-conversion tuner IC is de- signed for satellite set-top and very small aperture termi- nal (VSAT) applications. The device directly converts the satellite signals from the LNB to baseband using a broad- band 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 down-converting mixers, and baseband amplifiers. The RF variable-gain amplifier provides more than 70dB of gain control range. The device supports an RF bandwidth of 1GHz.
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 auto-select (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 shutdown while leaving the reference oscillator, digital interface, and buffer circuits active, providing a method to reduce power in single and multituner applications.
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
