Ehsan Azad
Research student, School of Engineering
- azadem@cardiff.ac.uk
- Room C/3.10, Queen's Buildings - Central Building, 5 The Parade, Newport Road, Cardiff, CF24 3AA
Overview
I am pursuing a Ph.D. research degree at the Centre for High-Frequency Engineering (CHFE) in the School of Engineering. The purpose of my research is to overcome challenges encountered in the design of non-linear RF and microwave power amplifiers for current and emerging markets.
My peers and I competed in two student design competitions for High-Efficiency Power Amplifiers (HEPA). As a team, we were awarded second place in the 2022 RWW/ARFTG MTT-S HEPA Student Design Competition, Las Vegas, USA; and third place in the 2021 IMS HEPA Student Design Competition.
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Research
Research interests
My research interests include the design, modelling, and characterization of nonlinear RF and microwave transistors and power amplifier circuits.
As part of my Ph.D. research, I am working with Ampleon Netherlands B.V on the design of highly efficient power amplifiers that can operate at multiple DC supply voltages. The design is based on the latest generation of gallium nitride (GaN) high electron mobility transistors (HEMTs) for sub-6 GHz 5G base stations.
Cardiff's nonlinear behavioural model is crucial to the design process since it allows us to use the nonlinear pull-load measurement data directly within the CAD simulator. This increases the possibility of a successful first-pass design.
A new mathematical formulation for the Cardiff model has been developed, which can predict the device behaviours at various DC supply voltages. Multiple peer-reviewed scientific papers have been published as a result of this accomplishment.
Teaching
I have more than 250 hours of experience as a lab demonstrator and teaching assistant in both undergraduate and postgraduate ectrical and electronic enginieering Modules. The modules which I have participated in are listed as below:
- MSc: Microwave and Millimetre-Wave Integrated Circuit Design and Technology.
- MSc: RF circuit design & CAD.
- Year one: Electrical and electronic engineering lab.
- Year one: Analogue and digital communication systems.
- Year one: Matlab surgery.
- Year one: Electrical and Electronic Engineering 1.
Thesis
Efficiency Improvement in Base Station Power Amplifiers
Funding source
Ampleon Netherlands B.V.
Supervisors
Publications
2024
- Azad, E. M., Chaudhry, K. A., Gannicliffe, J. and Quaglia, R. 2024. Design and experimental characterization of an asymmetric GaN MMIC Doherty power amplifier for Ka-Band transmitters. Presented at: 19th European Microwave Integrated Circuits Conference (EuMIC), Paris, France, 23-24 September 20242024 19th European Microwave Integrated Circuits Conference (EuMIC). IEEE pp. 158-161., (10.23919/eumic61603.2024.10732357)
- Tian, M., Bell, J. J., Quaglia, R., Azad, E. M. and Tasker, P. J. 2024. Artificial neural network nonlinear transistor behavioral models: Structure and parameter determination process based on the Cardiff Model. IEEE Transactions on Microwave Theory and Techniques (10.1109/TMTT.2024.3434959)
- van den Heuvel, I., Azad, E. M., Omisakin-Edwards, M., Cripps, S. C., Tasker, P. J. and Quaglia, R. 2024. A baseband impedance cancellation technique for wideband multi-transistor amplifiers. IEEE Microwave and Wireless Technology Letters 34(6), pp. 777-780. (10.1109/LMWT.2024.3390594)
2023
- Yuan, T., Quaglia, R., Chaudhry, K., Azad, E., Powell, J. R. and Cripps, S. C. 2023. Output signal re-injection in load modulated balanced amplifiers for RF bandwidth improvement. IEEE Microwave and Wireless Components Letters 33(10), pp. 1458-1461. (10.1109/LMWT.2023.3305812)
- Ghozati, S. U., Quaglia, R., Azad, E., Powell, J., Tasker, P. and Cripps, S. 2023. Load pull-driven behavioral modelling of microwave switches for the design of tunable reflective terminations. Presented at: EuMW 2024: European Microwave Week 2023, 19 - 21 September 2023.
- Tian, M., Bell, J., Azad, E., Quaglia, R. and Tasker, P. 2023. A novel Cardiff model coefficients extraction process based on artificial neural network. Presented at: 2023 IEEE Topical Conference on RF/Microwave Power Amplifiers for Radio and Wireless ApplicationsED, MAY BE LINKED, Las Vegas, NV, USA, 22-25 January 20232023 IEEE Topical Conference on RF/Microwave Power Amplifiers for Radio and Wireless Applications. IEEE, (10.1109/PAWR56957.2023.10046221)
- Azad, E. 2023. Efficiency improvement in base station power amplifiers. PhD Thesis, Cardiff University.
2022
- Azad, E. M., Quaglia, R., Chadhary, K., Bell, J. J. and Tasker, P. J. 2022. Cardiff model utilization for predicting the response of multiple-input power amplifiers. Presented at: Mediterrannean Microwave Symposium (MMS), Pizzo Calabro, Italy, 9-13 May 2022Proceedings of Microwave Mediterranean Symposium (MMS). IEEE, (10.1109/MMS55062.2022.9825516)
- Azad, E. M., Bell, J. J., Quaglia, R., Moreno Rubio, J. J. and Tasker, P. J. 2022. New formulation of Cardiff behavioral model including DC bias voltage dependence. IEEE Microwave and Wireless Components Letters 32(6), pp. 607-610. (10.1109/LMWC.2022.3140653)
- Azad, E. M., Quaglia, R., Bell, J. J., Chaudhry, K., Nghiem, A., Sulaksono, K. and Tasker, P. J. 2022. Load-pull data analysis of a GaN on SiC HEMT targeting multi bias Doherty design. Presented at: International Workshop on Integrated Nonlinear Microwave and Millimeterwave Circuits, INMMIC, Cardiff, UK, 7-8 April 2022Proceedings of the 2022 International Workshop on Integrated Nonlinear Microwave and Millimetre-Wave Circuits. IEEE, (10.1109/INMMiC54248.2022.9762106)
- Baddeley, A., Azad, E., Quaglia, R., Bell, J. and Tasker, P. 2022. Gate bias voltage dependence of Cardiff admittance model in Ka-band GaAs pHEMTs. Presented at: IEEE Topical Conference on RF/Microwave Power Amplifiers for Radio and Wireless Applications (PAWR), Las Vegas, NV, USA, 16-19 January 20222022 IEEE Topical Conference on RF/Microwave Power Amplifiers for Radio and Wireless Applications (PAWR). IEEE pp. 8-10., (10.1109/PAWR53092.2022.9719858)
- Azad, E. M., Quaglia, R., Bell, J. J., Chaudhry, K. and Tasker, P. J. 2022. DC-dependent Cardiff model from modulated supply and load-pull data. Presented at: 2022 Asia-Pacific Microwave Conference (APMC), Yokohama, Japan, 29 November 2022 - 02 December 2022Proceedings of 2022 Asia-Pacific Microwave Conference (APMC). IEEE pp. 181-183., (10.23919/APMC55665.2022.9999796)
2021
- Alimohammadi, Y. et al. 2021. Incorporating gate-lag effects into the Cardiff Behavioural Model. Presented at: 50th European Microwave Conference (EuMC 2020), Utrecht, Netherlands, 12-14 January 20212020 50th European Microwave Conference (EuMC). IEEE pp. 684-687., (10.23919/EuMC48046.2021.9338185)
2020
- Azad, E. M., Bell, J. J., Quaglia, R., Moreno Rubio, J. J. and Tasker, P. J. 2020. Gate bias incorporation into Cardiff behavioural modelling formulation. Presented at: IEEE/MTT-S International Microwave Symposium (IMS 2020), Los Angeles, CA, USA, 4-6 August 20202020 IEEE/MTT-S International Microwave Symposium (IMS). IEEE pp. 420-423., (10.1109/IMS30576.2020.9223817)