A 28-GHz CMOS-65 nm Dual Mode Class-J Doherty Power Amplifier With Integrated Class-G Driver and Impedance-Modulated- Quadrature-Transformer Achieving 21% Back-Off Efficiency
Document Type
Article
Publication Date
1-1-2025
Abstract
In this paper, a CMOS Class-J Doherty power amplifier (PA) integrating a Class-G driver and an Impedance-Modulated-Quadrature-Transformer (IMQT) to enhance back-off efficiency for multimode operations is presented. The Class-J Doherty PA utilizes a second harmonic termination to improve its efficiency. To further augment efficiency at deep back-off output power, a single-supply-rail Class-G driver operates with the IMQT, modulating the interstage impedance between the driver and the Doherty stages. The IMQT features a stacked transformer architecture and dynamically adjusts its impedance by switching a floating, intermediate coil between the transformer's primary and secondary windings. A comparator regulates the IMQT based on the Class-G driver's operation. The IMQT-DPA, fabricated using a 65nm CMOS process, operates at a center frequency of 28 GHz with a supply headroom of 1.8V. The PA achieves an average output power of 14 dBm with a back-off efficiency of 21%, representing a 1.4-fold efficiency enhancement compared to conventional Class-B operation. Under low-power mode (V-DD/2) with a Class-G driver operation, the average output power is 11.3 dBm with a 1.3-fold efficiency improvement.
Keywords
Coils, Transformers, Power amplifiers, Impedance, Modulation, Impedance matching, Switches, Power generation, Inductance, Capacitors, CMOS, Doherty, power amplifier (PA), quadrature-transformer, back-off efficiency, millimeter-wave, Ka-band, 5G, class-J, class-G
Publication Title
IEEE Access
DOI
10.1109/ACCESS.2025.3530958
Recommended Citation
Mariappan, Selvakumar; Rajendran, Jagadheswaran; Idros, Norhamizah; Sal Hamid, Sofiyah; Bin Abd Manaf, Asrulnizam; Kumar, Narendra; Alghaihab, Abdullah; Nathan, Arokia; and Siddik Yarman, Binboga, "A 28-GHz CMOS-65 nm Dual Mode Class-J Doherty Power Amplifier With Integrated Class-G Driver and Impedance-Modulated- Quadrature-Transformer Achieving 21% Back-Off Efficiency" (2025). Research Publications (2021 to 2025). 6163.
https://knova.um.edu.my/research_publications_2021_2025/6163
Funders
Ministry of Higher Education Malaysia for Fundamental Research Grant Scheme (FRGS/1/2024/TK07/USM/02/7),King Saud University (RSPD2024R806)
Volume
13
First Page
17236
Last Page
17245
Publisher
Institute of Electrical and Electronics Engineers