GMSK Packet Data Modem and RF Transceiver
CMX990
With a minimum of external components and circuits, this half-duplex device provides on-chip: a flexible,
formattable GMSK packet and freeformat modem, a dual operation synthesiser fed from an external
source, IF and RF stages for both Rx and Tx modes, and auxiliary ADCs and DACs for system control
and monitoring.
This versatile GMSK modem is programmable to both packet and freeformat data operations via an
efficient task-oriented Rx and Tx format and command structure, which is combined with data
scrambling, interleaving and FEC and CRC capabilities. Rx data acquisition, extraction and tracking
abilities, allied with Rx data quality feedback, allow the CMX990 to operate seamlessly in varying signal
environments.
IF and RF functions in the Tx path handle all the required signal mixing and up-conversion to produce
the FM modulation for the final external PA circuitry. In the Rx path these circuits provide initial
selectivity and rejection characteristics and mix down the inputs to provide baseband signals for the
modem.
Comprehensive internal and external system control and monitoring is provided by the 8-bit host
interface registers and the on-chip ADCs and DACs. Requiring a power supply input in the range 3.0 to
3.6 Volts, the CMX990 can be used in wireless products designed to comply with such standards as EN
300 113 and FCC CFR 47 Part 90. Operating over a temperature range of -40°C to +85°C, the CMX990
consolidates the core radio modem functions to enable a new generation of small, narrow-band wireless
data modems. The CMX990 comes in a 64-pin low profile VQFN package.
©
2004 CML Microsystems Plc
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