RF-CMOS Switched-Capacitor Power Amplifier for NB-IoT RF transceivers

• Autor(a) principal: Santos, Ana Isabel Ferreira dos
• Data de Publicação: 2023
• Tipo de documento: Dissertação
• Idioma: eng
• Título da fonte: Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos)
• Texto Completo: http://hdl.handle.net/10362/160970
• topic: SCPA; Matching Network; Cascoded Class-D; PAE; THD; CMOS; Domínio/Área Científica::Engenharia e Tecnologia::Engenharia Eletrotécnica, Eletrónica e Informática

The increasing market of Narrowband Internet of Things (NB-IoT) applications brings new challenges and constrains in the design of fully integrated transmission architectures, capable of delivering the desired output power with the highest efficiency and linearity, ensuring the longest battery lifetime of the devices. This work is focused on the study and implementation of the most power consuming block within the transmission chain: the Power Amplifier (PA). In this regard, a Switched Capacitor Power Amplifier (SCPA) is designed to operate at a frequency of 0.9 GHz and aiming the maximum output power allowed by the standard of 23 dBm. The final architecture includes a matching network that connects to eight unit PA cells through an LC filter. Each unit PA cell is made of a cascoded class-D PA, two drivers, a level shifter and two selection logic blocks. All the blocks were developed using RF components from a UMC 130nm CMOS process with a 1.2V/2.4V supply voltage. The results show that the architecture is able to produce a maximum output power of 15.61 dBm with a maximum Power Added Efficiency (PAE) of 26.52% and a Total Harmonic Distortion (THD) of 0.68%. In the same conditions, the measured HD2 and HD3 are of -70.23dBc and -43.41dBc, respectively. Additionally, a modulation stage was implemented in VerilogA in order to evaluate the impact of sending different symbols in the SCPA performance. The block, designed for a 16 QAM modulation, is responsible for generating both the number of unit PA cells to be selected and the phase of the clock connected to each PA cell, depending on the amplitude and phase of the constellation points being transmitted.