Discovery Semiconductors HLPD

Discovery Semiconductor is touting the use of its Highly Linear Photodiode (HLPD) technology to create optoelectronic clocks with low phase noise. Such clocks could enable ultra-fast analog-to-digital converters, among other advances, according to sources at the company.

The HLPD technology enables phase linearity of less than 5 rad/W, which Discovery Semiconductor claims is a record low. Nonlinear distortions can be further reduced by optimizing the photodiode’s bias, as Discover Semiconductor has done via the HLPD Lab Buddy instrument.

Discovery Semiconductor points to work performed at l’Observatoire de Paris as evidence of how such linearity can be leveraged to minimize the phase noise and timing jitter in optoelectronic systems.

“We recently used the HLPD Lab Buddy to generate, with femtosecond laser photonic source, 12-GHz microwave signals with a relative phase noise floor of about -155 dBc/Hz. This is thanks to the low shot-noise limit which arises from its high saturation power. This is the lowest noise level demonstrated so far with such a source,” commented scientists at LNE-SYRTE within the l’Observatoire de Paris via a Discovery Semiconductor press release.

The French scientists pointed to the usefulness of the technology in creating microwave sources with ultra-low phase noise for radar, very long baseline interferometry, or remote synchronization of large facilities. However, Dr. Shubo Datta, photonics engineer at Discovery Semiconductors, adds that clocks with low phase noise also can improve the speed of analog-to-digital converters, whose bandwidth and dynamic range have been historically limited by the synchronization issues arising from timing jitter.

Concluded Dr. Datta, “Several other applications of this instrument involve generating signals for high duty cycle with the resulting power dissipation in the photodiode approaching 0.5 W. Consequently, the HLPD Lab Buddy also allows controlling the temperature of the photodiode for the reliable performance in the entire range of its bias. The programmable bias and temperature control features of this instrument are designed to ease its integration into a myriad of laboratory applications, including testing the nonlinear distortions imparted by modulators and optical fibers.”

September 15, 2011

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