The MAX2140 complete receiver is designed for satellite digital audio radio services (SDARS). The device includes a fully monolithic VCO and only needs a SAW at the IF and a crystal to generate the reference frequency.
To form a complete SDARS radio, the MAX2140 requires only a low-noise amplifier (LNA), which can be controlled by a baseband controller. The small number of external components needed makes the MAX2140-based platform the lowest cost and the smallest solution for SDARS.
The receiver includes a self-contained RF AGC loop and baseband-controlled IF AGC loop, effectively providing a total dynamic range of over 92dB.
Channel selectivity is ensured by the SAW filter and by on-chip monolithic lowpass filters.
The fractional-N PLL allows a very small frequency step, making possible the implementation of an AFC loop. Additionally, the reference is provided by an external XTAL and on-chip oscillator. A reference buffer output is also provided.
A 2-wire interface (I²C bus compatible) programs the circuit for a wide variety of conditions, providing features such as:
- Programmable gains
- Lowpass filters tuning
- Individual functional block shutdown
The MAX2140 minimizes the requirement on the baseband controller. No compensation or calibration procedures are required. The device is available in a 7mm x 7mm 44-pin thin QFN package.
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