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Detalhes

Detalhes

006
Publicações

2020

Analysis and Design of a Polar Digitally Modulated CMOS PA Based on Switched Constant-Current

Autores
Gomes, R; Duarte, C; Pedro, JC;

Publicação
IEEE TRANSACTIONS ON MICROWAVE THEORY AND TECHNIQUES

Abstract
Typical polar digital power amplifiers (DPAs) employ unit-cells operated in class-E or D-1, denoting a switched-resistance operation which degrades linearity. Besides introducing higher demand on digital predistortion (DPD), it also requires extra quantization bits, impacting the overall efficiency and system complexity. To address this, the present work makes use of an optimized constant-current cascode unit-cell which is combined with reduced conduction angle to achieve linear and efficient operation, while minimizing the effort on DPD and/or calibration. A design strategy is developed which focuses on the cascode bias voltage and transistor relative dimensions as design parameters, allowing cascode efficiency optimization without compromising linearity or reliability. A single-ended polar switched constant-current DPA is implemented in 180-nm standard CMOS. Continuous-wave measurements performed at 800 MHz demonstrate an output power of 24 dBm with a PAE of 47%. The DPA dynamic behavior was tested with a 64-QAM signal with 10 MS/s, achieving an average PAE of 20.9% with a peak-to-average power ratio (PAPR) of 8.7 dB and adjacent-channel leakage ratio (ACLR) = 40.34 dB. These results demonstrate comparable performance with the prior art while using only 6-bits clocked at 100 MHz baseband sampling frequency.

2019

Design of an underwater sensor network perpetually powered from AUVs

Autores
Pessoa, LM; Duarte, C; Salgado, HM; Correia, V; Ferreira, B; Cruz, NA; Matos, A;

Publicação
OCEANS 2019 - Marseille

Abstract

2019

Experimental Evaluation of Coupling Coils for Underwater Wireless Power Transfer

Autores
Duarte, C; Goncalves, F; Silva, M; Correia, V; Pessoa, LM;

Publicação
2019 IEEE Wireless Power Transfer Conference (WPTC)

Abstract

2017

System design for wireless powering of AUVs

Autores
Ressurreicao, T; Goncalves, F; Duarte, C; Goncalves, R; Gomes, R; Santos, R; Esteves, R; Pinto, P; Oliveira, I; Pessoa, LM;

Publicação
OCEANS 2017 - Aberdeen

Abstract

2017

Performance improvement of a buck converter using Kalman filtering

Autores
Gora, W; Duarte, C; Costa, P; Pereira, A;

Publicação
International Journal of Power Electronics

Abstract

Teses
supervisionadas

2016

Digitally-Reconfigurable Transmitter for Emerging Wireless Communications

Autor
Rui Filipe de Pinho Gomes

Instituição
UA

2016

Circuit Optimization for Underwater Power Transfer

Autor
Francisco Ricardo Pinto Gonçalves

Instituição
UP-FEUP

2016

Process and Temperature Compensation of CMOS Ring Oscillators

Autor
Henrique Manuel Dias Cavadas

Instituição
UP-FEUP

2016

Subthreshold Circuits for the Internet of Things

Autor
Francisco Ricardo Pinto Gonçalves

Instituição
UP-FEUP

2016

Digitally-Modulated Transmitter for Wireless Communications

Autor
Rui Filipe de Pinho Gomes

Instituição
UP-FEUP