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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