ERASynth Micro

A USB-powered, low-priced, open source RF signal generator

Jun 18, 2019

Project update 5 of 12

Frequency Switching Speed

Frequency switching speed is defined as the time it takes for a signal generator (or a frequency synthesizer) to switch from one frequency to another. Frequency switching speeds of modern signal generators range from a few hundreds of nanoseconds to several hundred of milliseconds depending on the architecture and oscillator technology used. For example, one of the latest signal generators offered by Keysight, named UXG, has a frequency switching speeds as low as 180 ns. On the other hand, PSG series (possibly the purest microwave signal generator on the market) from the same manufacturer has around 9 ms.


We used an oscilloscope to measure ERASynth Micro’s frequency switching speed:


You might be wondering why we selected such low frequencies in the measurement. Why not measure the frequency switching speed at gigahertz frequencies? Well, for two reasons:

600 μs is respectable number for a signal generator considering the fact that we used an ATMEGA32U4 MCU to do all of the calculations and SPI transactions. Much better speed could be achieved if a more performant MCU with a higher clock was used.

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