Integrated RF synthesiser achieves low noise in low power applications
Low phase noise and what CML Microcircuits describes as “excellent spurious performance” is delivered in the low power CMX940, an integrated fractional-N RF synthesiser with voltage controlled oscillation.
According to CML Microcircuits, the CMX940 surpasses the industry prerequisites for enabling a new generation of private mobile radio (PMR), data modems, marine radios and other wireless systems.
The CMX940 is based on a dual-loop architecture with a configurable reference path, consisting of a separate phased locked loop (PLL) and voltage controlled oscillator (VCO). These are used to minimise close-in phase noise and mitigate integer and fractional boundary spurious.
Managing phase noise and spurious performance are required to meet international radio standards such as EN 300 113 and EN 300 086, mandated for narrow-band systems. The CMX940 has near noiseless clock multiplier technology which will deliver the high performance needed to meet these stringent requirements, confirms CML.
The CMX940 is capable of generating 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 needed to provide a compact and local oscillator (LO) source.
Many synthesisers targeting these application areas are based on a PLL IC with a large number of discrete external parts to implement the VCO, which consumes valuable PCB real estate. CML believes an integrated silicon design reduces component count / board area, eliminates VCO tolerancing issues and speeds up time to market.
At carrier frequency of 500MHz, the typical phase noise is -124 dBc/Hz at 12.5kHz offset and spurious products are better than -75dBc. The CMX940 operates from a 3.0 to 3.6V supply, with a current consumption of between 23 and 64mA depending on device configuration. These parameters make it particularly suitable for portable and battery powered applications.
CML Microcircuits designs, develops and supplies low-power analogue, digital and mixed-signal semiconductors for telecommunications systems globally.
The company’s varied portfolio means that CML devices are used in a range of industrial and commercial products for licensed and unlicensed wireless voice and data systems, for example digital/analogue PMR/LMR, wireless data, satellite communications and marine radio applications, such as TETRA, DMR, dPMR, SCADA systems and marine communications.
