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Dr James J W Bell
- Available for postgraduate supervision
Teams and roles for James J W Bell
Head of Teaching - Electrical and Electronic Engineering
Overview
James Bell is the Head of Teaching for the Electrical and Electronic Engineering and Integrated Engineering degree programs at Cardiff University. He received the bachelor’s and Ph.D. degrees from Cardiff University in 2009 and 2013 respectively. He has worked in the Centre for High Frequency Engineering here at Cardiff University, where he has been involved with the development of nonlinear measurement systems, the "Cardiff Model" and high-efficiency power amplifier design. He is currently a senior lecturer in the School of Engineering at Cardiff University and remains a member of the Centre for High Frequency Engineering. He continues his work in the areas of behavioural modelling, RF and millimeter-wave measurement systems, and broadband power amplifier design.
Publication
2025
- Tian, M. et al. 2025. Artificial neural network nonlinear transistor behavioral models: Structure and parameter determination process based on the Cardiff Model. IEEE Transactions on Microwave Theory and Techniques 73 (2), pp.745-759. (10.1109/TMTT.2024.3434959)
2024
- Tian, M. et al. 2024. An extraction method based on artificial neural network techniques for novel Cardiff model with reasonable extrapolation behavior. IEEE Microwave and Wireless Components Letters 34 (1), pp.5-8. (10.1109/LMWT.2023.3329979)
- Tian, M. et al. 2024. Application of the Cardiff Model for Orthogonal LMBA response prediction. Presented at: 2024 IEEE Topical Conference on RF/Microwave Power Amplifiers for Radio and Wireless Applications (PAWR) 21-24 January 2024. Proceedings Topical Conference on RF/Microwave Power Amplifiers for Radio and Wireless Applications (PAWR) 2024. IEEE. , pp.17-20. (10.1109/PAWR59907.2024.10438664)
2023
- Tian, M. et al. 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 2023. 2023 IEEE Topical Conference on RF/Microwave Power Amplifiers for Radio and Wireless Applications. IEEE. (10.1109/PAWR56957.2023.10046221)
- Yuan, W. , Tian, M. and Bell, J. 2023. Implementation efficiency comparison between ANN and the Cardiff Model in ADS. Presented at: 2023 International Workshop on Integrated Nonlinear Microwave and Millimeterwave Circuits, INMMIC 08-11 November 2023. 2023 International Workshop on Integrated Nonlinear Microwave and Millimetre-Wave Circuits (INMMIC). IEEE. , pp.1-4. (10.1109/INMMIC57329.2023.10321776)
2022
- Azad, E. M. et al. 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. et al. 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 2022. Proceedings of 2022 Asia-Pacific Microwave Conference (APMC). IEEE. , pp.181-183. (10.23919/APMC55665.2022.9999796)
- Azad, E. M. et al. 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 2022. Proceedings of the 2022 International Workshop on Integrated Nonlinear Microwave and Millimetre-Wave Circuits. IEEE. (10.1109/INMMiC54248.2022.9762106)
- Azad, E. M. et al. 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 2022. Proceedings of Microwave Mediterranean Symposium (MMS). IEEE. (10.1109/MMS55062.2022.9825516)
- Baddeley, A. et al. 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 2022. 2022 IEEE Topical Conference on RF/Microwave Power Amplifiers for Radio and Wireless Applications (PAWR). IEEE. , pp.8-10. (10.1109/PAWR53092.2022.9719858)
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 2021. 2020 50th European Microwave Conference (EuMC). IEEE. , pp.684-687. (10.23919/EuMC48046.2021.9338185)
2020
- Alimohammadi, Y. et al. 2020. Pulse profiling active load pull measurements. Presented at: IEEE/MTT-S International Microwave Symposium (IMS 2020) Los Angeles, CA, USA 4-6 August 2020. 2020 IEEE/MTT-S International Microwave Symposium (IMS). IEEE. , pp.759-762. (10.1109/IMS30576.2020.9223989)
- Azad, E. M. et al. 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 2020. 2020 IEEE/MTT-S International Microwave Symposium (IMS). IEEE. , pp.420-423. (10.1109/IMS30576.2020.9223817)
2019
- Al-Rawachy, A. et al., 2019. Behavioural model extraction using novel multitone active load-pull. Presented at: 2019 IEEE MTT-S International Microwave Symposium, IMS 2019 Boston, USA 2 -7 June 2019. MTT-S International Microwave Symposium (IMS). IEEE. , pp.196-199. (10.1109/MWSYM.2019.8700779)
- Husseini, T. et al. 2019. Global behavioural model generation using coefficients interpolation. Presented at: 2019 IEEE MTT-S International Microwave Symposium, IMS 2019 Boston, USA 2 -7 June 2019. , pp.-.
- Syed Anera, S. M. H. et al. 2019. High-efficiency broadband PA design based on continuous Class-F mode with compression. Presented at: 2019 IEEE MTT-S International Microwave Symposium, IMS 2019 Boston, USA 2 -7 June 2019. MTT-S International Microwave Symposium (IMS). IEEE. , pp.698-701. (10.1109/MWSYM.2019.8700767)
2018
- Bogusz, A. et al. 2018. Power and efficiency continuous modes in saturated GaN HEMT devices. Presented at: Inmmic 2018 Brive-La-Gaillarde, France 5- 6 July 2018.
- Husseini, T. et al., 2018. On the effective modeling of the test-set non-linearity. Presented at: 2018 91st ARFTG Microwave Measurement Conference (ARFTG) Philadelphia, PA, USA 15 June 2018. 2018 91st ARFTG Microwave Measurement Conference (ARFTG). IEEE. (10.1109/ARFTG.2018.8423832)
2017
- Quaglia, R. , Bell, J. J. and Cripps, S. 2017. New general formulation and experimental verification of harmonic clipping contours in high-frequency power devices. IEEE Transactions on Microwave Theory and Techniques 65 (10), pp.3903-3909. (10.1109/TMTT.2017.2687900)
2014
- Bell, J. J. 2014. Input Harmonic and Mixing Behavioural Model Analysis. PhD Thesis , Cardiff University.
- Koh, M. et al., 2014. Frequency scalable large signal transistor behavioral model based on admittance domain formulation. Presented at: International Microwave Symposium Tampa, Florida 1-6 June 2014. 2014 IEEE MTT-S International Microwave Symposium (IMS). Picastaway, NJ: IEEE. , pp.1-3. (10.1109/MWSYM.2014.6848287)
2013
- Aldoumani, A. et al. 2013. Operation and calibration of VNA-based large signal RF I-V waveform measurements system without using a harmonic phase reference standard. Presented at: ARFTG Microwave Measurement Conference (ARFTG) Seattle, WA 7-7 June 2013. 2013 81st ARFTG Microwave Measurement Conference (ARFTG). Picastaway, NJ: IEEE. , pp.1-4. (10.1109/ARFTG.2013.6579055)
- Koh, M. et al., 2013. X-band MMIC scalable large signal model based on unit cell behavioral data model and passive embedding network. Presented at: International Microwave Symposium Seattle, WA 2-7 June 2013. 2013 IEEE MTT-S International Microwave Symposium Digest (IMS). Picastaway, NJ: IEEE. , pp.1-4. (10.1109/MWSYM.2013.6697424)
2011
- Bell, J. J. et al. 2011. Behavioral model analysis using simultaneous active fundamental load-pull and harmonic source-pull measurements at X-band. Presented at: 2011 IEEE/MTT-S International Microwave Symposium Baltimore, MD, USA 5-10 June 2011. Microwave Symposium Digest (MTT), 2011 IEEE MTT-S International. New York: IEEE. , pp.982-986. (10.1109/MWSYM.2011.5972803)
- Powell, J. R. et al., 2011. GaAs X-band high efficiency (65%) broadband (30%) amplifier MMIC based on the Class B to Class J continuum. Presented at: 2011 IEEE/MTT-S International Microwave Symposium Baltimore, MD, USA 5-10 June 2011. Published in: Seigel, P. et al., 2011 IEEE/MTT-S International Microwave Symposium - MTT 2011. New York: IEEE. , pp.355. (10.1109/MWSYM.2011.5973350)
- Saini, R. et al. 2011. High speed non-linear device characterization and uniformity investigations at X-band frequencies exploiting behavioral models. Presented at: 2011 77th ARFTG Microwave Measurement Conference (ARFTG) Baltimore, MD, USA 10 June 2011. Design and Measurement of Microwave Systems - Proceedings of the 2011 77th ARFTG Microwave Measurement Conference (ARFTG). Los Alamitos, CA: IEEE(10.1109/ARFTG77.2011.6034552)
- Saini, R. et al. 2011. Interpolation and extrapolation capabilities of non-linear behavioural models. Presented at: 2011 78th ARFTG Microwave Measurement Symposium (ARFTG) Tempe, AZ, USA 1-2 December 2011. Proceedings of the 2011 78th ARFTG Microwave Measurement Symposium (ARFTG) - High Power RF Measurement Techniques. Los Alamitos, CA: IEEE(10.1109/ARFTG78.2011.6183865)
Articles
- Azad, E. M. et al. 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)
- Quaglia, R. , Bell, J. J. and Cripps, S. 2017. New general formulation and experimental verification of harmonic clipping contours in high-frequency power devices. IEEE Transactions on Microwave Theory and Techniques 65 (10), pp.3903-3909. (10.1109/TMTT.2017.2687900)
- Tian, M. et al. 2024. An extraction method based on artificial neural network techniques for novel Cardiff model with reasonable extrapolation behavior. IEEE Microwave and Wireless Components Letters 34 (1), pp.5-8. (10.1109/LMWT.2023.3329979)
- Tian, M. et al. 2025. Artificial neural network nonlinear transistor behavioral models: Structure and parameter determination process based on the Cardiff Model. IEEE Transactions on Microwave Theory and Techniques 73 (2), pp.745-759. (10.1109/TMTT.2024.3434959)
Conferences
- Al-Rawachy, A. et al., 2019. Behavioural model extraction using novel multitone active load-pull. Presented at: 2019 IEEE MTT-S International Microwave Symposium, IMS 2019 Boston, USA 2 -7 June 2019. MTT-S International Microwave Symposium (IMS). IEEE. , pp.196-199. (10.1109/MWSYM.2019.8700779)
- Aldoumani, A. et al. 2013. Operation and calibration of VNA-based large signal RF I-V waveform measurements system without using a harmonic phase reference standard. Presented at: ARFTG Microwave Measurement Conference (ARFTG) Seattle, WA 7-7 June 2013. 2013 81st ARFTG Microwave Measurement Conference (ARFTG). Picastaway, NJ: IEEE. , pp.1-4. (10.1109/ARFTG.2013.6579055)
- 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 2021. 2020 50th European Microwave Conference (EuMC). IEEE. , pp.684-687. (10.23919/EuMC48046.2021.9338185)
- Alimohammadi, Y. et al. 2020. Pulse profiling active load pull measurements. Presented at: IEEE/MTT-S International Microwave Symposium (IMS 2020) Los Angeles, CA, USA 4-6 August 2020. 2020 IEEE/MTT-S International Microwave Symposium (IMS). IEEE. , pp.759-762. (10.1109/IMS30576.2020.9223989)
- Azad, E. M. et al. 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 2020. 2020 IEEE/MTT-S International Microwave Symposium (IMS). IEEE. , pp.420-423. (10.1109/IMS30576.2020.9223817)
- Azad, E. M. et al. 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 2022. Proceedings of 2022 Asia-Pacific Microwave Conference (APMC). IEEE. , pp.181-183. (10.23919/APMC55665.2022.9999796)
- Azad, E. M. et al. 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 2022. Proceedings of the 2022 International Workshop on Integrated Nonlinear Microwave and Millimetre-Wave Circuits. IEEE. (10.1109/INMMiC54248.2022.9762106)
- Azad, E. M. et al. 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 2022. Proceedings of Microwave Mediterranean Symposium (MMS). IEEE. (10.1109/MMS55062.2022.9825516)
- Baddeley, A. et al. 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 2022. 2022 IEEE Topical Conference on RF/Microwave Power Amplifiers for Radio and Wireless Applications (PAWR). IEEE. , pp.8-10. (10.1109/PAWR53092.2022.9719858)
- Bell, J. J. et al. 2011. Behavioral model analysis using simultaneous active fundamental load-pull and harmonic source-pull measurements at X-band. Presented at: 2011 IEEE/MTT-S International Microwave Symposium Baltimore, MD, USA 5-10 June 2011. Microwave Symposium Digest (MTT), 2011 IEEE MTT-S International. New York: IEEE. , pp.982-986. (10.1109/MWSYM.2011.5972803)
- Bogusz, A. et al. 2018. Power and efficiency continuous modes in saturated GaN HEMT devices. Presented at: Inmmic 2018 Brive-La-Gaillarde, France 5- 6 July 2018.
- Husseini, T. et al., 2018. On the effective modeling of the test-set non-linearity. Presented at: 2018 91st ARFTG Microwave Measurement Conference (ARFTG) Philadelphia, PA, USA 15 June 2018. 2018 91st ARFTG Microwave Measurement Conference (ARFTG). IEEE. (10.1109/ARFTG.2018.8423832)
- Husseini, T. et al. 2019. Global behavioural model generation using coefficients interpolation. Presented at: 2019 IEEE MTT-S International Microwave Symposium, IMS 2019 Boston, USA 2 -7 June 2019. , pp.-.
- Koh, M. et al., 2013. X-band MMIC scalable large signal model based on unit cell behavioral data model and passive embedding network. Presented at: International Microwave Symposium Seattle, WA 2-7 June 2013. 2013 IEEE MTT-S International Microwave Symposium Digest (IMS). Picastaway, NJ: IEEE. , pp.1-4. (10.1109/MWSYM.2013.6697424)
- Koh, M. et al., 2014. Frequency scalable large signal transistor behavioral model based on admittance domain formulation. Presented at: International Microwave Symposium Tampa, Florida 1-6 June 2014. 2014 IEEE MTT-S International Microwave Symposium (IMS). Picastaway, NJ: IEEE. , pp.1-3. (10.1109/MWSYM.2014.6848287)
- Powell, J. R. et al., 2011. GaAs X-band high efficiency (65%) broadband (30%) amplifier MMIC based on the Class B to Class J continuum. Presented at: 2011 IEEE/MTT-S International Microwave Symposium Baltimore, MD, USA 5-10 June 2011. Published in: Seigel, P. et al., 2011 IEEE/MTT-S International Microwave Symposium - MTT 2011. New York: IEEE. , pp.355. (10.1109/MWSYM.2011.5973350)
- Saini, R. et al. 2011. High speed non-linear device characterization and uniformity investigations at X-band frequencies exploiting behavioral models. Presented at: 2011 77th ARFTG Microwave Measurement Conference (ARFTG) Baltimore, MD, USA 10 June 2011. Design and Measurement of Microwave Systems - Proceedings of the 2011 77th ARFTG Microwave Measurement Conference (ARFTG). Los Alamitos, CA: IEEE(10.1109/ARFTG77.2011.6034552)
- Saini, R. et al. 2011. Interpolation and extrapolation capabilities of non-linear behavioural models. Presented at: 2011 78th ARFTG Microwave Measurement Symposium (ARFTG) Tempe, AZ, USA 1-2 December 2011. Proceedings of the 2011 78th ARFTG Microwave Measurement Symposium (ARFTG) - High Power RF Measurement Techniques. Los Alamitos, CA: IEEE(10.1109/ARFTG78.2011.6183865)
- Syed Anera, S. M. H. et al. 2019. High-efficiency broadband PA design based on continuous Class-F mode with compression. Presented at: 2019 IEEE MTT-S International Microwave Symposium, IMS 2019 Boston, USA 2 -7 June 2019. MTT-S International Microwave Symposium (IMS). IEEE. , pp.698-701. (10.1109/MWSYM.2019.8700767)
- Tian, M. et al. 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 2023. 2023 IEEE Topical Conference on RF/Microwave Power Amplifiers for Radio and Wireless Applications. IEEE. (10.1109/PAWR56957.2023.10046221)
- Tian, M. et al. 2024. Application of the Cardiff Model for Orthogonal LMBA response prediction. Presented at: 2024 IEEE Topical Conference on RF/Microwave Power Amplifiers for Radio and Wireless Applications (PAWR) 21-24 January 2024. Proceedings Topical Conference on RF/Microwave Power Amplifiers for Radio and Wireless Applications (PAWR) 2024. IEEE. , pp.17-20. (10.1109/PAWR59907.2024.10438664)
- Yuan, W. , Tian, M. and Bell, J. 2023. Implementation efficiency comparison between ANN and the Cardiff Model in ADS. Presented at: 2023 International Workshop on Integrated Nonlinear Microwave and Millimeterwave Circuits, INMMIC 08-11 November 2023. 2023 International Workshop on Integrated Nonlinear Microwave and Millimetre-Wave Circuits (INMMIC). IEEE. , pp.1-4. (10.1109/INMMIC57329.2023.10321776)
Thesis
- Bell, J. J. 2014. Input Harmonic and Mixing Behavioural Model Analysis. PhD Thesis , Cardiff University.
Research
James' research interests include, but are not limited to, behavioural modelling, intelligent measurement systems, and power amplifier design. He is currently working on robust automated load-pull measurement systems; augmenting the 'Cardiff Behavioural Model' framework for measurement system control and robust CAD models for PA design; and the practical application of 'Clipping Contours' for the design of linear or linearisable PAs. James works closely with international industry and academics, as his research impacts both sectors.
Teaching
Head of Teaching for Electrical and Electronic Engineering and Integrated Engineering
EN1217 Applied Design and Practice (Module Leader)
EN2710 Group Design Project (Module Contributor)
EN2810 Integrated Product Design (Module Contributor)
EN3818 Analogue and Digital Communications Systems (Module Contributor)
EN4110 Mechatronics (Module Contributor)
Biography
Professional memberships
Member of the IEEE
Supervisions
Supervised Areas
- Artificial Intelligence
- Active device modelling
- Machine learning RF and mm-wave measurement and modelling solutions
- Intelligent load-pull measurement systems
- Power amplifier theory and design
Current supervision
Derek Kozel
Lucas Yuan
Contact Details
[email protected]
+44 29208 79378
Queen's Buildings - South Building, Floor 3, Room S3.11, 5 The Parade, Newport Road, Cardiff, CF24 3AA
+44 29208 79378
Queen's Buildings - South Building, Floor 3, Room S3.11, 5 The Parade, Newport Road, Cardiff, CF24 3AA
Research themes
Specialisms
- AI
- Modelling and simulation
- Measurement Systems and PA Design