Cambridge Consultants claims first for “all-digital radio transmitter”

March 05, 2015 // By Graham Prophet
Cambridge Consultants reports that it has successfully completed initial trials of the first fully digital radio transmitter, calling it a “turning point” in wireless design and a real enabler for the ‘Internet of Things’ (IoT) and 5G technology.

The concept is that digital circuitry – logic – generates a binary pattern with edge and pulse timing that directly forms the RF spectral output required; imposing modulated content is entirely carried out in the digital space. Similar ideas have been proposed for some time, and (somewhat) related activity has seen a great deal of effort go into area such as ultra-wideband signal generation or “impulse radio”, where very fast pulse edges in the time domain equate to signals at or below noise level that spread across a wide part of the spectrum.

CCL’s announcement describes digital circuitry directly feeding an antenna, but it seems reasonable to assume that for any significant RF power output an RF power amplifier would be required; but given the nature of the signal chain, not necessarily a linear amplifier.

CCL clarifies, “Unlike ‘software-defined radio’ (SDR), it’s not a mixture of analogue and digital components – for the first time, the radio is completely digital, which can enable new ways of using spectrum intelligently.” CCL is not new to RF innovation, having spun off the group that became Cambridge Silicon Radio (CSR) and that was first to develop a workable single-chip Bluetooth radio.

This development is codenamed Pizzicato (“plucking with the finger, the strings of a violin or other stringed instrument” - an allusion, presumably, to generating spectral content with a pulsed stimulus) and CCL sees it as a route to “unlock the potential of the IoT”. “It opens the door to a new dynamic way in which the predicted billions of IoT devices can operate together in a crowded radio spectrum. And it will enable the creation of 5G systems, with multiple radios and antennas.”

The Pizzicato digital radio transmitter consists of an integrated circuit outputting a single stream of bits, and an antenna – with no conventional radio parts or digital-to-analogue converter. Algorithms perform the necessary ultra-fast computations in real time, making it