Analog beamforming at 60 GHz

The large unlicensed frequency band internationally available around 60 GHz makes it attractive to support gigabit per second wireless applications, such as uncompressed high-definition video streaming and large file transfers.

However, 60 GHz communications must overcome many challenges. One of them is the poor link budget: the free-space path loss, which is proportional to the square of the frequency, is substantially higher at 60 GHz than at the lower frequencies being used by mobile networks or wireless local networks.

A possible solution to improve the link budget is to perform analog beamforming, ie, analog in-phase combination of the signals received at multiple antennas. Analog beamforming is preferred to digital beamforming because it is cheaper and allows the use of one analog-to-digital converter.

IMEC has obtained convincing results on analog beamforming with its 60 GHz receiver, including both its proprietary analog front-end integrated circuit in 45 nm CMOS technology and patch antennas using PCB technology.

Beamforming is achieved with RF phase shifting, controllable by a PC. Phase shifting in RF has cost and design advantages, as it requires only one mixer which also simplifies the local oscillator distribution.