Skip to main content
eScholarship
Open Access Publications from the University of California

UC San Diego

UC San Diego Electronic Theses and Dissertations bannerUC San Diego

Digital Switching CMOS Power Amplifier for Multiband and Multimode Handset Applications /

  • Author(s): Nakatani, Toshifumi
  • et al.
Abstract

This thesis is directed towards the development of a digitally-assisted radio frequency power amplifier (RF PA) which is one of the potential solutions to realize a multiband and multimode transmitter with high efficiency for handset applications. To improve efficiency and linearity in multiple conditions, PA circuits and digital signal processing (DSP) algorithms are co-designed. In the dissertation, a proposed architecture employs a current- mode class-D (CMCD) configuration for high efficiency, and a polar modulation scheme driven by digital inputs. Detail design, fabrication and experimental results are given for circuit implementation and DSP of this architecture. First, a multiband watt-class complementary metal-oxide- semiconductor (CMOS) PA is demonstrated using 0.15 um CMOS integrated circuits (ICs), off-chip inductor and balun. To obtain high breakdown voltage, stacked field effect transistors (FETs) are used. The CMCD PA is tuned by band- switching capacitors, operating in the 0.7-1.8 GHz frequency band. The overall efficiencies of 27.1 / 25.6 % are achieved at 30.2 / 28.9 dBm CW output powers and 0.85 / 1.75 GHz carrier frequencies, respectively. Next, to achieve wide output power dynamic range, an architecture consisting of small segmented unti-cells is introduced into the PA, where multiple three-state unit-cells are used and the state of each unit-cell is controlled to provide a specific output power. The overall dynamic ranges are expanded to approximately 90 dB and 85 dB at and 0.85 / 1.75 GHz, respectively. The dissertation then presents digital modulation algorithms. The digital compensation techniques are developed to maintain linearity of an envelope modulator of the polar transmitter. A new digital pulse width modulation algorithm is also shown to partially suppress spurious signals associated with the digital input envelope signal. When wideband code-division multiple access (WCDMA) modulation is implemented, spur suppression of 9-10 dB is achieved while maintaining adjacent channel leakage power ratios within 3rd generation partnership project specifications

Main Content
Current View