| dc.description.abstract | This thesis presents a study on the design and performance analysis of power amplifiers (PAs) utilizing envelope tracking (ET), or drain modulation, techniques to enhance their efficiency. The focus of this research is centered on two separate 2.4 GHz PAs, each capable of delivering a 30 dBm peak output power, as well as the design of a dual-band PA intended to operate at both 2.4 GHz and 5.2 GHz, delivering a 30 dBm output power as well. In addition to this, a fourth, previously designed PA, is produced and measured. The specifications of these amplifiers are based on performance demands from the nrF7002 WiFi companion integrated circuit (IC).
The very first part of the study investigates the performance of the chosen transistor to be used, through measurements of both the transistor by itself and as part of the previously designed PA. After this, the focus shifts to the design of a single-band PA operating in class A at a down-shifted frequency of 2.3 GHz, optimized for a 300 mA drain current. Through the design process, the amplifier achieves a maximum output power above 30 dBm, gain as high as 12.37 dB with static drain voltage, and with drain modulation employed an average power added efficiency (PAE) of up to 19.90 \% while maintaining high linearity.
The second single-band PA operates at the same frequency but sits in class AB with a 65 mA drain current, even though initially designed for a 50 mA. This design iteration shows a maximum output power just above 30 dBm, gain as high as 11.46 dB with static drain voltage, and with drain modulation employed an average PAE of up to 41.87 \% while maintaining similar linearity to the 300 mA version.
In an effort to improve system flexibility, better suiting the demands of the nRF7002, the thesis explores the design of a dual-band PA capable of amplifying both 2.4 GHz and 5.2 GHz signals. The amplifier achieves an output power of approx. 30 dBm at the again down-shifted frequency of 2.3 GHz. At this frequency, the highest gain achieved is 12.17 dB with static drain voltage, and with drain modulation employed, an average PAE of up to 10.95 \% while maintaining relatively high linearity.
For the higher frequency of the dual-band device, down-shifted from 5.2 to 5.15 GHz, the discrepancy between simulated and measured values is significant and the gain is practically limited, reaching a maximum value of just above 1 dB, not making it relevant to look further into efficiency metrics. However, a maximum output power of not too far below 30 dBm is reached.
A 16QAM is used for the measurements providing the performance metrics, while a test with 64QAM as well is performed with the lower frequency of the dual-band PA. | |
