dc.description.abstract | The thesis developed three power amplifiers that were designed in tsmcTM 0.18-μm complementary metal oxide semiconductor (CMOS) processes for 5th generation communication system applications.
Chapter 2 presents an n79-band CMOS single-ended stacked power amplifier with continuous class-B mode techniques. In order to improve harmonic interference characteristics in this designed circuit, continuous class-B technique is used in the output matching network to suppress the second harmonic distortion. By selecting the bias point, the gain compression caused by the third-order harmonic is suppressed, resulting in a power amplifier that maintains linear output power when operating with large signals, with the measured output power at 1-dB gain compression point being close to the output saturation power. The maximum measured gain is 14.15 dB, and the saturated output power within the frequency band ranges from 21 dBm to 21.5 dBm, with an efficiency of 12.1% to 14.45%. The output power at 1-dB gain compression is from 20.27 dBm to 20.86 dBm. The chip area is 2.58 mm2. Modulation signal measurements were performed using a 100 MHz 256QAM signal with an input power level of 5 dBm. Digital Predistortion (DPD) was applied, improving the EVM from 3.15% to 1.65%, and the ACPR from -27.61/-32.20 dBc to -30.06/-37.77 dBc, with an output peak power of 21.04 dBm.
In Chapter 3, a differential tightly coupled transformer stacked power amplifier for the n79 frequency band is proposed. By using magnetic-coupled transformers to combine two power cells, and the output parasitic capacitance of the power cells is reduced, the output impedance is double, and the better matching to the system is achieved. A tightly coupled transformer is designed for the output matching network to improve transmission efficiency, and transistor bias points that suppress the third-order harmonic are selected to mitigate the impact of harmonics on the circuit. The maximum measured gain is 15.22 dB. The saturated output power within the frequency band ranges from 21.82 dBm to 23.55 dBm, with an efficiency of 8% to 10.22%. The output power at 1-dB gain compression is from 14.1 dBm to 20.7 dBm. The chip area is 3.79 mm2. Modulation signal measurements were performed using a 100 MHz 256QAM signal with an input power level of 9 dBm. DPD was applied, and the measurement results showed that the tightly coupled circuit has good resistance to interference in the modulation signal, eliminating the need for DPD. Without DPD, at an input power of 9 dBm, the output peak power reached 22.1 dBm with an EVM of 3.3%.
Additionally, Chapter 3 also presents a differential compact transformer-stacked power amplifier for the n79 frequency band is proposed. The inter-stage matching network uses a center-tapped inductor, which is a balnced-to-balanced magnetic-coupled transformer. The output matching network is optimized using parallel coupling layout to reduce the length of metal trace, minimize loss, and thus increase the Q factor, thereby improving the transmission efficiency of the output balun. The differential coupled transformer-stacked power amplifier is compacted to a chip area of 2.57 mm2. The maximum measured gain is 12.3 dB. The saturated output power within the frequency band ranges from 21.8 dBm to 22.6 dBm, with an efficiency of 8% to 9.8%. The output power at 1-dB gain compression is from 19.8 dBm to 20.7 dBm. Modulation signal measurements were performed using a 100 MHz 256QAM signal with an input power level of 6 dBm. DPD was applied, improving the EVM from 4% to 2%. | en_US |