Multi-Gigabit Wireless Link using W-Band Phased Array Chipset - Page 1
Forum section: electronics / projects

author: Hugoneus
author_rank: Frequent Contributor
timestamp: June 02, 2015, 08:32:19 pm
content: Hi everyone,I have been busy with work and the MTT conference. Since I haven't had a chance to release a video, I thought I would let you know what I have been busy doing.We had a live demo of a wireless link setup at MTT during our presentation which is capable of establishing a link (beyond) 32Gb/s at a carrier of 92GHz using two polarization. This uses the phased array chipset that I designed at Bell Labs. Each chipset has 16RX/4TX or 16TX/4RX phased array elements with up- and down-converters, integrated PLL, various calibration, self-test, etc. Two dies are flip-chipped directly onto PCB (die-on-PCB) with the phased array antennas integrated onto the PCB. This is no easy task at 92GHz! The EIRP at 90GHz is about 34dBm which is a record in itself at W-band.I can try answering some questions as long as it is within released information about this project.

author: R_G_B_
author_rank: Frequent Contributor
timestamp: June 02, 2015, 09:16:38 pm
content: Can you combine this technique with other diversity techniques to improve the speed much further than 32Gb/sR_G_B

author: ConKbot
author_rank: Super Contributor
timestamp: June 02, 2015, 10:30:46 pm
content: Sounds very interesting! What sort of stimulation software is being used with this? I'm assuming this is to the point where even on die interconnects are controlled impedance? Any laser trimming or is the stimulation and fabrication good enough that it's ready to go after dicing? could on die antennas (patch?) Be a possiblity in the future? Hows the 3rd harmonic on the transmitter?

author: Lukas
author_rank: Frequent Contributor
timestamp: June 02, 2015, 10:54:15 pm
content: Some questions:How do you get data in/out of the chips?What material is the chip made out of?What modulation does it use / what's the modulation bandwidth?What's the phased array stuff used for? Spatial multiplexing/MIMO or just to get the radiation pattern right?Was the the chip first time right?Is there a paper/publication?

author: Hugoneus
author_rank: Frequent Contributor
timestamp: June 02, 2015, 11:21:46 pm
content: Some answers to your questions:The IC is designed in Cadence. It is a SiGe BiCMOS process with fT/fMAX of about 240GHz/270GHz.The interface to the IC is baseband I/Q with up to 7.5GHz of bandwidth per side. (15GHz of RF bandwidth).The modulation is adaptive and depends on the link quality. This is controlled by the modem ranging using various QAM.Phased array is used for spatial beam forming.There is a paper, it is published at RFIC 2015 which was held last month.

author: Howardlong
author_rank: Super Contributor
timestamp: June 02, 2015, 11:31:33 pm
content: Am I right to assume that this is for point to point links and that the phased arrays are fixed, i.e. no clever dynamic beam steering?I had enough trouble building WR42 waveguide filters connected to LO, mixer and 30dBm amp 15 years ago for narrowband K band, let alone the sort of stuff you're doing. I guess waveguide's a bit old fashioned these days.

author: Dago
author_rank: Frequent Contributor
timestamp: June 03, 2015, 05:02:50 am
content: Sounds tremendously interesting! I've always wondered what you do for work. I've also recently been very interested in microwave stuff (currently building a FMCW radar).Do you have any pictures of the system/PCB and could you share them?

author: Hugoneus
author_rank: Frequent Contributor
timestamp: June 03, 2015, 05:19:35 am
content: Quote from: Howardlong on June 02, 2015, 11:31:33 pmBeam steering algorithms are handled by the modem and often at the firmware level.

author: Hugoneus
author_rank: Frequent Contributor
timestamp: June 03, 2015, 05:20:54 am
content: Quote from: Dago on June 03, 2015, 05:02:50 amFMCW at what frequency?Unfortunately the PCB photo isn't released yet, although I did show it during the conference presentation which is not distributed.

author: coppice
author_rank: Super Contributor
timestamp: June 03, 2015, 05:35:08 am
content: Quote from: Dago on June 03, 2015, 05:02:50 amIs FMCW (or FMICW) still an interesting kind of radar to build these days?

author: Dago
author_rank: Frequent Contributor
timestamp: June 03, 2015, 07:09:47 am
content: Quote from: Hugoneus on June 03, 2015, 05:20:54 amIt is for 4.2-4.4 GHz altimeter band. By changing the VCO it would be easy to use it for 2.45 or 5.8 GHz too (just need to redesign the bandpass filter and swap the VCO) but the noise levels are very high and bandwidth is very low on those ISM bands. Also have lots of stuff for a 10 GHz YIG-oscillator based one.A pic of the PLL+VCO board (PLL not locked yet):http://www.dgkelectronics.com/storage/electronics/fmcw_radar/vco_synth/pll_vco_working.jpgHairpin bandpass filter:http://www.dgkelectronics.com/storage/electronics/fmcw_radar/hairpin_filter/hairpin_filter_v2.jpgQuote from: coppice on June 03, 2015, 05:35:08 amI've found it fascinating. Involves lots of system level design, RF design, analog design, digital (embedded) stuff, software work (embedded and desktop)...Question for Shahriar: How long did this project last? Maybe even split to design phase, prototyping phase etc.

author: daqq
author_rank: Super Contributor
timestamp: June 03, 2015, 11:58:05 am
content: This area of electronics is a completely amazing and alien realm for me...What kind of spacial/length/time tolerance can you afford in such systems?

author: nfmax
author_rank: Super Contributor
timestamp: June 03, 2015, 01:54:19 pm
content: Are you using any sort of adaptation in the beam-steering, to cope with mechanical tolerances or temperature-dependent changes in phase shift, or is it a one-time set-up?

author: Hugoneus
author_rank: Frequent Contributor
timestamp: June 03, 2015, 05:09:56 pm
content: Quote from: Dago on June 03, 2015, 07:09:47 amGreat work!The project took about 1 year from transistor circuit design to demonstration.

author: Marco
author_rank: Super Contributor
timestamp: June 03, 2015, 05:22:45 pm
content: How much useful bandwidth remains if it has to use a bounce off another surface?

author: Hugoneus
author_rank: Frequent Contributor
timestamp: June 03, 2015, 06:13:44 pm
content: Quote from: Marco on June 03, 2015, 05:22:45 pmA couple of issues arise. The coherent bandwidth may be affected as well as multipath may cause fading at certain frequencies. There is also the issue of polarization scrambling due to reflection. All of these effects would be addressed at the modem layer.

author: vaualbus
author_rank: Frequent Contributor
timestamp: June 03, 2015, 09:11:45 pm
content: Quote from: Hugoneus on June 03, 2015, 06:13:44 pmSo your team/you have also work on some algorithm for the modem layer?The project is similar to the one you post a photo a while back on the blog?

author: rfdave#gmail.com
author_rank: Contributor
timestamp: June 04, 2015, 02:47:22 am
content: I saw you there talking to the Rohde & Schwartz guys!

author: Hugoneus
author_rank: Frequent Contributor
timestamp: June 04, 2015, 10:48:21 pm
content: Quote from: rfdave#gmail.com on June 04, 2015, 02:47:22 amI wish you had come and said hello!

author: R_G_B_
author_rank: Frequent Contributor
timestamp: June 05, 2015, 04:45:39 pm
content: What type of forward error correction are you using?R_G_B

author: rfdave#gmail.com
author_rank: Contributor
timestamp: June 08, 2015, 01:14:09 am
content: Quote from: Hugoneus on June 04, 2015, 10:48:21 pmYou looked like you were having a good discussion. Maybe next conference, I'll introduce myself.