A CMOS Polar Class-G Switched-Capacitor PA With a Single High-Current Supply, for LTE NB-IoT and eMTC

• Published in: IEEE journal of solid-state circuits 2019-07, Vol.54 (7), p.1941-1951
• Main Authors: Bechthum, Elbert, El Soussi, Mohieddine, Dijkhuis, Johan F., Mateman, Paul, van Schaik, Gert-Jan, Breeschoten, Arjan, Liu, Yao-Hong, Bachmann, Christian
• Format: Article
• Language: English
• Subjects: Capacitors; Cat-M1; Cat-NB1; Class-G; CMOS; Efficiency; enhanced machine type communication (MTC); High current; long term evolution (LTE); narrow band (NB)-IoT; Peak to average power ratio; Phase shift keying; Phasor measurement units; power amplifier (PA); Power amplifiers; Power efficiency; Power management; Power supplies; Radio frequency; single-supply Class-G; switched-capacitor (SC) PA; Systems analysis; Transmitters
• ISSN: 0018-9200; 1558-173X
• DOI: 10.1109/JSSC.2019.2910407

Class-G efficiency enhancement of switched-capacitor (SC) power amplifiers (PAs) requires the power management unit (PMU) to have two high-current power supplies. This paper presents a Class-G efficiency enhancement that only requires one single high-current power supply with a lower bandwidth requirement, significantly simplifying the PMU. The system analysis shows that a transmitter with a resolution of 13 bits and a sample rate of F_{RF}/2 meets the requirements of the Cat-M1 and Cat-NB1 standard. The presented PA consists of a number of parallel SC cells. Each cell can be configured in two output-power modes, using only a single supply. At 807 MHz, the peak output power is 27.1 dBm, with an efficiency (PAE) of 33.3%. The efficiency at −6 and −12 dB FS is 22.5% and 14.4%, respectively, which is an improvement of 1.3\times and 1.7\times compared to Class-B. The 13-bit resolution enables a power-control range for Cat-M1 and Cat-NB1 signals of >63 dB. In that range, the error vector magnitude (EVM) is