By Graham K. Rogers

The piezoelectric properties of quartz and certain other materials (including bone) has many uses. Apply pressure to a piece of quartz and it will create an electric current. If an electric current is applied, the material will vibrate and as these materials vibrate at known rates they are useful in electronic applications, such as the clock in a computer. "They are used to generate frequencies to control and manage virtually all communication systems (Jauch Quartz)."

Epson has been producing a number of voltage-controlled crystal oscillators VCXO) for a while, but limits with some of these VCXOs required optical transmission equipment to use either a single fixed-frequency oscillator which had to be swapped out to change frequencies or multiple fixed-frequency oscillators which increased board space and cost.

The latest VG7050EAN and VG7050ECN oscillators can be programmed over a range of 50 MHz to 800 MHz. They also have low jitter rates and consume less power than any other VCXO currently available. The solution to the earlier problems was to combine a high-frequency fundamental (HFF) crystal with a low-jitter fractional-n PLL IC to produce reliable crystal technology with better phase noise and jitter.

VG7050EAN (left) and VG7050ECN (right)

While the two new oscillators are factory-programmed for optimal performance, settings may be over-written, thus allowing users to select any output frequency and absolute pull rate desired.

A PDF of features and specifications for the VG7050EAN and VG7050ECN is available online. Also available are data sheets for,

• VG7050EAN
• VG7050ECN

Graham K. Rogers teaches at the Faculty of Engineering, Mahidol University in Thailand where he is also Assistant Dean. He wrote in the Bangkok Post, Database supplement on IT subjects. For the last seven years of Database he wrote a column on Apple and Macs.