Wednesday, October 7, 2020 — 12:00 PM EDT

Candidate: Soroush Rasti Boroujeni

Title: Active-Antenna Front-Ends for Large Phased-Array Transmitters

Date: October 7, 2020

Time: 12:00 PM

Place: REMOTE ATTENDANCE

Supervisor(s): Safavi-Naeini, Safieddin

 

Abstract:

The ever-increasing demand for wireless broadband connectivity requires infrastructures that can support multi-Gbps of data transfer. To facilitate such a heavy traffic demand, the channel capacity for the given spectrum should be utilized more efficiently. Wideband millimeter-wave phased-array systems can enhance the capacity of the channel by providing multiple steerable directional beams. The cost, complexity and high power consumption of phased-array systems are the key barriers to commercializing this technology. Silicon-based beam-former chips along with scalable phased-array technology offer promising solutions for lowering the cost of phased-array systems. However, the implementation of low-power phased-array architectures is still a challenge. The millimeter wave power generation in silicon beam-formers suffers from low efficiency, and  the stringent linearity requirements for multi-beam wide-band arrays further limit the efficiency. In scalable phased-arrays, each module consists of an antenna sub-array and a beam-former chip that feeds the antenna elements.  Improving overall efficiency requires a design methodology that considers the beam-former chip and the antenna array as one entity. This thesis presents power efficient solutions for mm-wave phased-array transmitter and proposes different high efficiency power amplifier structures for broadband applications.

 

A 27-30 GHz RF front-end consisting of a variable gain amplifier, a 360 degree phase shifter, and a two-stage linear power amplifier with the output power of 12 dBm is fabricated using 0.13 µm SiGe technology. The measurement results show 26.7% total efficiency for this chip. This chip is the RF-core of a beam-former chip with eight outputs for feeding 2×2 dual feed sub-arrays for large phased-arrays used in SATCOM. This chip achieved the highest efficiency among the reported Ka-band phased-array transmitters.

 

Furthermore, novel transformer based output matching structures are proposed for harmonic-tuned power amplifiers. Harmonic tuned power amplifiers have high peak-efficiency but their complicated output matching structure was limiting their use in beam-former RF front-ends. The proposed output matching structures have a layout footprint of a transformer and make their application in beam-former chips possible. A 26-38 GHz power amplifier based on non-inverting 1:1 transformer is fabricated. The measured efficiency of higher than 27% across the band and output power of 12 dBm is achieved. Furthermore, two continuous class F-1 power amplifiers using a 1:1 inverting transformer are implemented. Simulation results show the peak-efficiency of 35% and output power of 12 dBm from 24 to 30 GHz. A common-base power amplifier with inverting transformer output matching is also demonstrated. This amplifier has a peak-efficiency of 42% and peak output power of 16 dBm.

 

Lastly, a low loss Ka-band re-configurable output matching structure based on tunable lines is proposed and implemented. A double stub matching structure with three tunable segments is introduced to maximize the impedance matching coverage. This structure can potentially compensate for the antenna impedance variation in phased-array antennas.

Location 
REMOTE PARTICIPATION


,

S M T W T F S
29
30
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
1
2
  1. 2021 (1)
    1. January (1)
  2. 2020 (231)
    1. December (5)
    2. November (18)
    3. October (16)
    4. September (15)
    5. August (16)
    6. July (32)
    7. June (29)
    8. May (32)
    9. April (27)
    10. March (13)
    11. February (20)
    12. January (16)
  3. 2019 (282)
    1. December (16)
    2. November (32)
    3. October (19)
    4. September (26)
    5. August (26)
    6. July (40)
    7. June (24)
    8. May (23)
    9. April (35)
    10. March (25)
    11. February (9)
    12. January (10)
  4. 2018 (150)
  5. 2017 (212)
  6. 2016 (242)
  7. 2015 (242)
  8. 2014 (268)
  9. 2013 (192)
  10. 2012 (31)