Direct-Conversion Tuner ICs for Digital DBS Applications

The MAX2102/MAX2105* are low-cost direct-conversion tuner ICs designed for use in digital direct-broadcast satellite (DBS) television set-top box units. The direct-conversion architecture reduces system cost compared to devices with IF-based architectures.

The MAX2102/MAX2105 directly tune L-band signals to baseband using a broadband I/Q downconverter. Operating frequency range spans from at least 950MHz to 2150MHz.

The ICs include a low-noise amplifier (LNA) with automatic gain control (AGC), two downconverter mixers, an oscillator buffer with 90° quadrature generator and prescaler, and baseband amplifiers.

The MAX2102 features an AGC range of 50dB, allowing input power levels as low as -69dBm. The MAX2105 has a reduced AGC range of 41dB and accepts input power levels down to -60dBm. The reduced AGC range of the MAX2105 allows the use of a high-gain external LNA to achieve a lower system noise figure (NF).

Applications

* Broadband Systems * Cell Phone Base Stations * DBS Tuners * DVB-Compliant DBS Tuners * LMDS * Wireless Local Loop (WLL)

* Low-Cost Bipolar Design, Lowest Cost Architecture

* Operate from a Single +5V Supply

* 950MHz to 2150MHz Input Frequency Range*

* On-Chip Quadrature Generator, Dual-Modulus Prescaler (/64, /65)

* Input Levels

* 69dBm to -19dBm per Carrier (MAX2102)

* -60dBm to -19dBm per Carrier (MAX2105)

* Over 50dB AGC Control Range (MAX2102)

* Noise Figure = 13.2dB (MAX2102); IP3 = 6.5dBm (at 1450MHz)

* Automatic Baseband Offset Correction

* Easy Interface to MAX1002/MAX1003 Dual ADC and Popular Baseband ICs