As someone who started his career in broadcasting and then live sound, the Integrated Systems Europe show in Amsterdam is one where I especially enjoy meeting past colleagues as well as new contacts. This year at ISE 2015, Hall 2, Stand 2-E60 we will be exhibiting something quite revolutionary: Pizzicato™, the world's first completely digital radio transmitter. That’s a digital-only chip feeding the antenna directly – no conventional radio parts or even digital-to-analogue converter.
My colleague Jez Stark and I will demonstrate a single chip generating 14 GSM/EDGE base station transmissions spread across 80 MHz of spectrum, with a standard mobile signal test set measuring a standards-compliant signal for each. Pizzicato uses patent-pending algorithms to achieve the ultra-fast computations – required for the multi-gigabit per second stream – to be performed in real time without degrading the signal. This world first comes from Cambridge Consultants’ multi-disciplinary wireless development team, demonstrating close coupling of architecture and algorithm into a highly-optimised design.
How might this be of interest to the AV world? Well, it can be a very low-cost and low-powered transmitter indeed. On a 28nm CMOS chip, we estimated its silicon area to be less than 1mm2, and its power consumption under 300mW – while driving up to 1mW into the antenna at 1.5GHz. It’s completely frequency agile, and the modem on the chip could be either analogue FM or any sort of digital one. Inter-transmitter (“back”) intermodulation effects would be absent, helping with spectral efficiency in today’s spectral squeeze.
Of course, the idea of building entire radios entirely from software and digital signal processing is not new – it’s been around for decades. The digital part has been slowly taking over the lower-frequency parts of all radios – in broadcast transmitters just as in your smartphone – but a complete takeover remained out of reach, mostly because each time the digits got faster, the benefit was been absorbed in an increased demand from the radio systems – higher carrier frequencies, for example. This Software Defined Radio (SDR) allowed huge increases in efficiency, but still depended on analogue technology for the high frequency parts of the radio.
But not any more! My colleague Monty Barlow describes the advances in technology here. The especially exciting part is that the performance of an all-digital radio will improve with Moore’s Law – that digital chips get twice as good every 18 months or so. Today, a fast generally-available digital technology allows us to transmit 1 GHz of radio bandwidth, anywhere up to 14 GHz carrier frequency. Next year, we’ll be able to do even more!