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
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 efficien...
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| Main Authors: | , , , , , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
IEEE
2025-01-01
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| Series: | IEEE Access |
| Subjects: | |
| Online Access: | https://ieeexplore.ieee.org/document/10844314/ |
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| Summary: | 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 (VDD/2) with a Class-G driver operation, the average output power is 11.3 dBm with a 1.3-fold efficiency improvement. |
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| ISSN: | 2169-3536 |