OCXO delivers ultra low phase noise performance

October 09, 2013 // By Graham Prophet
IQD's IQOV-200F OCXO delivers exceptional phase noise performance with a close-in measurement of -130 dBc at 100 Hz and a noise floor better than -180 dBc across a high frequency range of 80 to 130 MHz.

The IQOV-200F uses a specially designed circuit to allow optimisation of phase noise and jitter during production. There is a complex relationship between the crystal, the oscillator circuit, the internal voltage regulation circuit and the output buffer which all contribute to noise in the system. Designing a circuit which isolates these elements and allows specific tuning to optimise each has been a key part of IQD's research and development work for this product range and a critical success is the ability to apply this to an automated production line.

In addition to the challenges of the oscillator circuit, the crystal is a critical component in any OCXO design and especially where close-in phase noise performance is of high priority. IQD's engineering team has developed a predictive test system to allow the phase noise of crystals to be measured before mounting in the oscillator circuit. This has allowed the team to focus research specifically on the effects of changes in the crystal production process and tighter control of plating, bonding and sealing processes have been key areas of improvement within SC-cut crystal production.

Combining the high performance expected from an IQD SC-cut crystal based OCXO, the IQOV-200F delivers a frequency stability of ±50 ppb over the standard -20 to 70°C operating temperature range. Housed in a 36 x 27 mm “Eurostyle” package and running off a 12 V supply, the unit offers a sinewave output of 13 dBm minimum. Any frequency from 80 to 130 MHz can be ordered whilst optional pulling can also be specified. IQOV-200F offers comparatively low power consumption of 150 mA maximum at 25°C and 350 mA max during warm up.

The product is suitable for any application where phase noise is a critical design consideration, where references are multipled to the GHz range, such as test and measurement systems and radar.

Other examples of applications where low phase noise is a key parameter include Dielectric Resonator