Get under an AWG's hood

Regardless of architecture, most AWGs use some form of memory sequencing to increase their effective memory.

By Martin Rowe, Senior Technical Editor -- Test & Measurement World, 10/11/2010 9:49:22 AM

Arbitrary waveform generators (AWGs) let you create just about any signal. An AWG's internal architecture includes memory, a processor, and a digital-to-analog converter. How the instrument creates waveforms from that memory can vary depending on the instrument's architecture.

Download the paper "Waveform generators vary in architecture," by Joan Mercadé of Arbitrary Resources.

Some instruments have a "true-arb" architecture that produces an analog voltage for every point in memory sequentially, varying the sample rate. Direct-digital synthesis, another popular architecture, uses a constant sample rate but skips samples to lower its effective output rate. Interpolating AWGs may oversample a signal to produce  flat frequency and linear-phase responses over the instrument's specified bandwidth. Finally, an interleaving architecture interleaves two channels to produce a single signal with a higher frequency or at a greater length that is obtainable through a single channel.

Regardless of architecture, most AWGs use some form of memory sequencing to increase their effective memory by letting you repeat a memory segment. That reduces the memory needed to produce a waveform or segment when used more than once in an output signal.

You can learn more about how AWGs produce signals, how they use memory, and how they minimize artifacts caused by discontinuities in waveform segments by downloading the paper "Waveform generators vary in architecture," by Joan Mercadé of Arbitrary Resources.