The MAX2104 low-cost direct-conversion tuner IC is designed for use in digital direct-broadcast satellite (DBS) television set-top box units. Its direct-conversion architecture reduces system cost compared to devices with IF-based architectures. The MAX2104 directly converts L-band signals to baseband signals using a broadband I/Q downconverter. The operating frequency range extends from 925MHz to 2175MHz.
The IC includes an LNA gain control, I and Q downconverting mixers, lowpass filters with gain control and frequency control, a local oscillator (LO) buffer with a 90° quadrature network, and a charge-pump based PLL for frequency control. The MAX2104 also has an on-chip LO, requiring only an external varactor-tuned LC tank for operation. The output of the LO drives the internal quadrature generator and dual modulus prescaler. An on-chip crystal amplifier drives a reference divider as well as a buffer amplifier to drive off-chip circuitry. The MAX2104 is offered in a 48-pin TQFP-EP package.
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