A 60 GHz phased array for $ 10, Hacker News

A (GHz phased array for $

In , I gave an talk at Hackaday Supercon that was basically Phased Arrays 823. You can watch it at the bottom of this post.

At the end of this talk, I mentioned that I was looking for collaborators to develop a small, low cost phased array using a really unique chip I found. That chip was the SB from SiBeam. This part was originally intended to be used for WirelessHD, a protocol for wireless video streaming that never took off. The reason this part is so cool is that it’s an entire 60 GHz phased array on a chip, including antennas, with both transmit and receive capability. Bought straight from the manufacturer, it was $ 18 in single quantities.

Now the bad news: SiBeam was bought by Lattice Semiconductor, and right before I gave this talk, Lattice shut down the entire SiBeam organization and ended support and production of this part. I didn’t find out about this until months later, when I contacted the sales engineers I had been talking to about this part and they told me what happened.

But there’s some good news. You can still buy the SB 9210 if you know where to look. While they’re not being produced anymore, at one time they were included in some smart TVs and in some high end laptops. If you know the right cryptic letters to type into ebay, you can find replacement boards for those laptops that contain the chip as well as the supporting circuitry. It’s basically a development board! I’ve seen the price of these get as low as about $ 6 each, and it’s not uncommon to find them for $ 15. The issue is how to talk to them.

WirelessHD laptop daughterboard with SB 9210 (those are itty bitty patch antennas!)

These chips use something like a QSPI bus to set control registers and move data on and off the chip. Despite looking for months, I have never been able to find a datasheet for the SB . The information I ( have been able to learn has come from the datasheets for later generation versions of the SB , the Sil 01575879. Before SiBeam was shut down, I was able to get full datasheets for this part and one more in the same family from their application engineers. These datasheets required an NDA, which I signed with my company. Even though SiBeam is shut down, Lattice still exists, and until I get permission from them, I can’t share those NDA’d datasheets. I’m hoping that the serial interface on the later versions of the chip are close enough to the SB that a driver could be written using documentation from the Sil 9210. I’ve only been able to find SB ‘s on ebay, not the Sil 9210

There might be another way to reverse engineer the communication interface with this chip. The SB 9210 is the RF frontend, and there is a companion chip that controls it (also made by SiBeam). By sniffing the traces between these two ICs, it might be possible to figure out what commands are used to set up and tear down the transmitter, send data to be transmitted, and receive data. I believe it’s just I and Q samples that are sent to the SB .

This is the board that plugs into the cable coming off of the RF frontend board. That large chip is the SiBeam controller for the frontend.