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Bridging the gap

A Tabor Electronics product story
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Edited by the Electronicstalk editorial team Feb 7, 2006

Between low-end affordable arbitrary function generators and high-end expensive arbitrary waveform generators, Ron Glazer argues that Tabor's Wonder Wave Series offers the best of both worlds.

Traditional function generators (FG or SFG) are analogue generators based on voltage-controlled analogue triangle-wave oscillators that deliver limited standard waveforms.

Various other waveforms may be created by shaping the base triangle.

For example, a square wave is created by driving the analogue triangle through a comparator which is switched at the triangle's midpoints.

Another example is distorting the triangle wave via a diode-shaping network to provide a reasonably pure sinewave.

Although analogue generators can output all the standard waveforms throughout the entire frequency range, they have their shortcomings.

Some are associated with poor resolution and accuracy.

Others relate to their limited waveform capabilities which prevent users from capturing, creating and playing real-life waveforms.

Arbitrary/function generators (AFGs) are digital generators based on a direct digital synthesis (DDS) system, characterised by a fixed sample clock rate (that allows the use of only one output filter) and fixed lookup table length.

The addressing scheme used in this system is known as a phase accumulator.

An increase in frequency is achieved by skipping addresses in the lookup table, using fewer samples and completing the cycle in fewer steps using