MMIC-based Low Phase Noise Millimetre-wave Signal Source Design
Doctoral thesis, 2019

Wireless technology for future communication systems has been continuously evolving to meet society’s increasing demand on network capacity. The millimetre-wave frequency band has a large amount of bandwidth available, which is a key factor in enabling the capability of carrying higher data rates. However, a challenge with wideband systems is that the capacity of these systems is limited by the noise floor of the local oscillator (LO). The LO in today’s communication systems is traditionally generated at low frequency and subsequently multiplied using frequency multipliers, leading to a significant degradation of the LO noise floor at millimetre-wave frequencies. For this reason, the thesis considers low phase noise millimetre-wave signal source design optimised for future wideband millimetre-wave communications.

In an oscillator, low frequency noise (LFN) is up-converted into phase noise around the microwave signal. Thus, aiming for low phase noise oscillator design, LFN characterisations and comparisons of several common III-V transistor technologies, e.g. GaAs-InGaP HBTs, GaAs pHEMTs, and GaN HEMTs, are carried out. It is shown that GaN HEMTs have good potential for oscillator applications where far-carrier phase noise performance is critical, e.g. wideband millimetre-wave communications.

Since GaN HEMT is identified as an attractive technology for low noise floor oscillator applications, an in-depth study of some factors which affects LFN characteristics of III-N GaN HEMTs such as surface passivation methods and variations in transistor geometry are also investigated. It is found that the best surface passivation and deposition method can improve the LFN level of GaN HEMT devices significantly, resulting in a lower oscillator phase noise.

Several MMIC GaN HEMT based oscillators including X-band Colpitts voltage-controlled-oscillators (VCOs) and Ka-band reflection type oscillators are demonstrated. It is verified that GaN HEMT based oscillators can reach a low noise floor. For instance, X-band GaN HEMT VCOs and a Ka-band GaN HEMT reflection type oscillator with 1 MHz phase noise performance of -135 dBc/Hz and -129 dBc/Hz, respectively, are demonstrated. These results are not only state-of-the-art for GaN HEMT oscillators, but also in-line with the best performance reported for GaAs-InGaP HBT based oscillators. Further, the MMIC oscillator designs are combined with accurate phase noise calculations based on a cyclostationary method and experimental LFN data. It has been seen that the measured and calculated phase noise agree well.

The final part of this thesis covers low phase noise millimetre-wave signal source design and a comparison of different architectures and technological approaches. Specifically, a fundamental frequency 220 GHz oscillator is designed in advanced 130 nm InP DHBT process and a D-band signal source is based on the Ka-band GaN HEMT oscillator presented above and followed by a SiGe BiCMOS MMIC including a sixtupler and an amplifier. The Ka-band GaN HEMT oscillator is used to reach the critical low noise floor. The 220 GHz signal source presents an output power around 5 dBm, phase noise of -110 dBc/Hz at 10 MHz offset and a dc-to-RF efficiency in excess of 10% which is the highest number reported in open literature for a fundamental frequency signal source beyond 200 GHz. The D-band signal source, on the other hand, presents an output power of 5 dBm and phase noise of -128 dBc/Hz at 10 MHz offset from a 135 GHz carrier signal. Commenting on the performance of these two different millimetre-wave signal sources, the GaN HEMT/SiGe HBT source presents the best normalized phase noise at 10 MHz, while the integrated InP HBT oscillator demonstrates significantly better conversion efficiency and still a decent phase noise.



low frequency noise

phase noise


signal source



deposition method.


frequency multiplier



Kollektorn, MC2, Kemivägen 9, Chalmers University of Technology
Opponent: Prof. Olivier Llopis, French National Center for Scientific Research (CNRS) Toulouse, France


Thi Ngoc Do Thanh

Chalmers, Microtechnology and Nanoscience (MC2), Microwave Electronics

A 110-to-147 GHz Frequency Sixtupler in a 130 nm Sige Bicmos Technology

EuMIC 2018 - 2018 13th European Microwave Integrated Circuits Conference,; (2018)p. 105-108

Paper in proceedings

7-13 GHz MMIC GaN HEMT Voltage-Controlled-Oscillators (VCOs) for Satellite Applications


Paper in proceedings

A MMIC GaN HEMT Voltage-Controlled-Oscillator with high tuning linearity and low phase noise

2015 IEEE Compound Semiconductor Integrated Circuit Symposium, CSICS 2015,; (2015)

Paper in proceedings

Low frequency noise measurements-A technology benchmark with target on oscillator applications

2014 44th European Microwave Conference, EuMC 2014 - Held as Part of the 17th European Microwave Week, EuMW 2014; Fiera di RomaRome; Italy; 6 October 2014 through 9 October 2014,; (2014)p. 1412-1415

Paper in proceedings

T. N. T. Do, M. Bao, Z. S. He, A. Hassona, D. Kuylenstierna, H. Zirath, "A low phase noise D-band signal source based on 130 nm SiGe BiCMOS and 0.15 µm AlGaN/GaN HEMT Technologies,” in International Journal of Microwave and Wireless Technologies, vol. 11, special issue 5-6, Jun. 2019, pp. 456-465

T. N. T. Do, H. Zirath, D. Kuylenstierna, "220 GHz Oscillator in 130 nm InP HBT MMIC Technology,” manuscript, submitted to IEEE Microwave Theory and Techniques (MTT), Sept. 2019.

The growth of data traffic in the society keeps increasing year by year. This pushes wireless technology for future communication systems toward innovations to achieve higher capacity. In order to increase the capacity of a single communication channel, a larger channel bandwidth or an improved spectral efficiency is required. For a fixed channel bandwidth, the spectral efficiency can be improved by increasing the number of encoded bits for each symbol transmitted on a microwave carrier in point–to–point communication. However, for each increasing order of modulation level, there is 3-dB degradation in receiver sensitivity. There is a certain demand on signal-to-noise (SNR) ratio of the receiver when using a high order modulation technique. Current communication systems already address relatively high order modulation level and the capacity of these systems can be considered to be limited by bandwidth. In order to meet the increasing demand of data rates, higher frequency and large absolute bandwidth available at millimetre-wave frequencies are used. However, a challenge of wideband millimetre-wave systems which need to support simultaneously large bandwidth and high order modulation technique is the local oscillator (LO) phase noise floor.

In the design of an oscillator, low frequency noise (LFN) characterisation is of special interest since LFN will be up-converted into phase noise around the microwave signal. Besides, methods to reduce LFN level in a transistor, e.g. different passivation methods, are of concern for low phase noise oscillator design since they can lead to an improvement in oscillator phase noise.

In this work, techniques for design of low-noise millimetre-wave frequency signal source optimised for wideband millimetre-wave communication systems to enable higher data rates are presented. The covered topics are: low frequency noise (LFN) characterisations and comparisons of different transistor technologies for low phase noise oscillator design, methods to improve LFN characteristic of III-Nitride GaN HEMTs and MMIC low phase noise signal source design combining with accurate phase noise calculation based on time-invariant method.  Several state-of-the-art MMIC GaN HEMT based oscillators are reported in this work. Further, two millimetre-wave signal sources realised by two different architectures with state-of-the-art performances are demonstrated. The first millimetre-wave signal is generated at the fundamental 220 GHz based on the advanced 130 nm InP DHBT process while the second signal is generated at the fundamental 23 GHz based on GaN HEMT technology and multiplied to the D-band by a state-of-the-art SiGe BiCMOS sixtupler.

Areas of Advance

Information and Communication Technology


Kollberg Laboratory

Chalmers Infrastructure for Mass spectrometry

Driving Forces

Innovation and entrepreneurship

Subject Categories

Electrical Engineering, Electronic Engineering, Information Engineering

Learning and teaching

Pedagogical work



Doktorsavhandlingar vid Chalmers tekniska högskola. Ny serie: 4652


Chalmers University of Technology

Kollektorn, MC2, Kemivägen 9, Chalmers University of Technology

Opponent: Prof. Olivier Llopis, French National Center for Scientific Research (CNRS) Toulouse, France

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