Fully integrated RF synthesiser for low power applications

02-12-2020 | CML Micro | Semiconductors

CML Microcircuits has launched the CMX940, a fully integrated Fractional-N RF synthesiser with VCO that attains low phase noise and exceptional spurious performance in a low power single-chip solution. The device exceeds the industry requirements for allowing a new generation of private mobile radio, data modems, marine radios and other wireless systems.


To achieve high performance and flexibility in a low power solution, the company has executed a dual-loop architecture with a highly-configurable reference path, comprising a separate PLL and VCO, utilised to minimise close-in phase noise and mitigate integer and fractional boundary spurious.


Managing phase noise and spurious performance is essential to satisfying international, including ETSI, radio standards such as EN 300 113 and EN 300 086, mandated for narrow-band systems. The device has numerous design innovations such as a near noiseless clock multiplier technology which will provide the high performance required to satisfy these stringent demands.


The CMX940 can generate RF signals over a continuous frequency range from 49MHz to 2040MHz, with dual single-ended RF outputs to support Rx and Tx sub-systems. Only an external loop filter and clock reference are required to deliver a compact and high-quality LO source.


At carrier frequency of 500MHz, the typical phase noise is -124dBc/Hz at 12.5kHz offset, and spurious products are better than -75dBc. The device works from a 3V to 3.6V supply, with a current consumption of between 23mA and 64mA depending on device configuration, making it an excellent choice for portable and battery-powered applications.

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