Practically every piece of communications equipment today has some sort of frequency reference. Many require two very precise and stable references, and they usually have to meet stringent phase noise specifications. The Dual Frequency Reference Module (DFRM) from NEL Frequency Controls addresses these needs (see the figure).
The DFRM consists of two ultra-low phase-noise oven-controlled crystal oscillators (OCXOs) at 10 MHz and 100 MHz that are phase-locked together to provide a fully characterized plug-and-play solution. The good news is that you get the best performance features of both frequency references in one package: the outstanding close-in phase noise, stability, and aging of a 10-MHz OCXO coupled with the superior phase noise on the floor of a 100-MHz OCXO.
Additionally, the DFRM offers two frequency outputs: 10 and 100 MHz. It boasts 2-ppb peak-to-peak temperature stability and low aging from 0.25 ppb/day. Its short-term stability Allan variance (AVAR) is less than 1E-12 at 1 s. And, its ultra-low phase noise totals –115 dBc/Hz at 1-Hz offset, • –145 dBc/Hz at 10-Hz offset for 10 MHz, –125 dBc/Hz at 10-Hz offset, and –180 dBc/Hz at 100 kHz for 100 MHz.
The DFRM operates from 12- and 5-V supplies and consumes 2.5 W. The outputs are both sine waves at a level of +13 dBm. Spectral purity is typically –90 dBc at 100 MHz. Common applications include telecommunications equipment, high-performance synthesizers, radar, and instrumentation.
