Flexible Multi-Channel Phase-Coherent 1GSps Radio Frequency Source

FlexDDS is a multi-channel phase-coherent Radio Frequency source. The design directly addresses the needs of experimental physicists who want to control all signal parameters in real-time from a computer. Initially, a series of actions (like changes in amplitude or frequency, start of frequency sweeps, etc.) is compiled into commands which are then transferred to the FlexDDS-Rack via a USB link. Each time a (real-time asynchronous) trigger input is activated, FlexDDS-Rack executes one or several commands and waits for the next trigger event. There is no limit to the number of successive commands as they are loaded continuously from the host computer.

One outstanding feature of FlexDDS is its defined and known phase relationship between channels. For example, two channels can easily be set up to produce a Radio Frequency output at the same frequency and with an equal phase (or specified phase offset). Slightly detuning the frequency of one channel will then linearly increase the phase difference between the two channels.

Note: This product is no longer recommended. There is a next generation multi-channel version called FlexDDS-NG with a flexible Ethernet interface as well as a new dual-channel version called FlexDDS-NG DUAL.


  • Multi-channel operation with precisely known and adjustable phase relationship between channels
  • Real-time control of all signal parameters
  • Phase-continuous frequency tuning
  • Computer interface (e.g. USB 2.0 link, optional RS-232)
  • New: PDCPU Add-On: Per-Slot processor with 32 ns cycle time and 8192 instruction deep memory for added flexibility and fast real-time control of DDS parameters.


  • FlexDDS-Rack: 19" rack which integrates the computer interface and power supplies
  • The rack can hold up to 8 independent FlexDDS Radio Frequency generator slots and 1 frontpanel controller slot (FlexDDS-FPCtl)
  • FlexDDS: Radio Frequency generator slot module
  • FlexDDS-FPCtl: Slot module for reference clock and trigger.

Sample output waveforms

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