As the demand for wireless electronics is increasing, more and more gadgets are connected wirelessly and devices are being improved constantly. The need of the new research and development for advance electronics with high performances is the priority. The data transfer rates are improved for faster communication and better efficiency is to reduce the battery consumption in handheld devices.
This thesis presents three single-stage power amplifiers (PAs): class-AB, class-F and inverse class-F (class-F-1) at 28 GHz. The PAs have identical input networks: input matching, base DC feed, and base stabilizing networks. At the load side, there is a different load network for each PA. Class-AB PA load network has a single inductor with a parasitic capacitor to create a resonance at 28GHz. Class-F PA load network is composed of a parallel network (one LC tank in series with an inductor) and a series network (one 3f0-resonance LC tank in series with a capacitor) to create a multi-resonance load network. Class-F-1 load network is composed of a parallel network (two LC tank in series with an inductor) and a series network (one 2f0-resonance LC tank in series with a capacitor) to have a multi-resonance network. The main purpose of using multi-resonance load networks in class-F and class-F-1 is to shape the collector currents and voltages in order to achieve the highest efficiency possible.
The chosen bias point is VCE=2.3V and ICE~12mA. As the results, class-AB PA achieves the peak PAE of 44%, 15 dBm OP-1dB, >19 dBm Psat , and 10 dB Gp. Class-F PA achieves the peak PAE of 46%, 14.5 dBm OP-1dB, ~18 dBm Psat , and 10 dB Gp. Class-F-1 PA achieves the peak PAE of 45%, 15.1 dBm OP-1dB, >18 dBm Psat , and 10 dB Gp.. In order to compare the linearity performances among three PA classes, a two-tone signal and a modulated signal with different modulation schemes (QPSK, 16QAM, 64QAM, and 256QAM) are applied to the PAs to produce IM3, ACPR, and EVM. After the analysis and comparison on efficiency and linearity, class-F PA gives the highest efficiency but has the worst linearity while class-AB has the best linearity but has the worst efficiency among three. Class-F-1 PA results lies in the middle of two other classes in term of efficiency and linearity. / Master of Science / As the demand for wireless electronics is increasing, more and more gadgets are connected wirelessly and devices are being improved constantly. The data transfer rates are improved for faster communication and better efficiency is to reduce the battery consumption in handheld devices.
A power amplifier is a very essential component in many microwave and millimeterwave systems. This thesis presents the designs of three different RF power amplifiers (PAs), which belongs to three different types of PAs: class-AB PA, class-F PA, and inverse class-F (class-F<sup>-1</sup>) PA. Each PA is designed to show distinct behaviors at a very high frequency around 28 GHz. Some portions of the designs are very identical among three classes. Three PAs have different circuit portions at the output side, which affect the performances of the PAs. There exists a capacitance from the transistor architecture, so called parasitic capacitance (C<sub>P</sub>). In class-AB PA output, a single inductor is used to create a resonance with C<sub>P</sub>. In class-F and class-F<sup>-1</sup> PA outputs, the combination of inductors and capacitors results in resonances at fundamental frequency (f<sub>0</sub>), second harmonic (2f<sub>0</sub>), and third harmonic (3f<sub>0</sub>) depending on the impedance requirements of each PA. The main purpose is to shape the voltage and current waveforms in order to obtain the highest performances possible.
The voltage and current supplied to the PA are chosen to achieve high power and efficiency at the output of the PAs. The most important parameters in PA design are efficiency and linearity. Efficiency is the effectiveness of the DC power conversion process from supplies into microwave power, which can be expressed as the ratio between output power and supplied DC power. Linearity is a term synonymous with fidelity in an audio amplifier. The term refers to the essential job of an amplifier to increase the power level of an input signal without otherwise altering the content of the signal. After the analysis and comparison on power efficiency and linearity, class-F PA gives the highest efficiency but has the worst linearity while class-AB has the best linearity but has the worst efficiency among three. Class-F<sup>-1</sup> PA results lies in the middle of two other classes in term of efficiency and linearity.
| Identifer | oai:union.ndltd.org:VTETD/oai:vtechworks.lib.vt.edu:10919/75312 |
| Date | 07 March 2017 |
| Creators | Phan, Diem Thanh |
| Contributors | Electrical and Computer Engineering, Koh, Kwang-Jin, Raman, Sanjay, Ha, Dong S. |
| Publisher | Virginia Tech |
| Source Sets | Virginia Tech Theses and Dissertation |
| Detected Language | English |
| Type | Thesis |
| Format | ETD, application/pdf |
| Rights | In Copyright, http://rightsstatements.org/vocab/InC/1.0/ |
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