0.7–1.8 GHz multiband digital polar transmitter using watt-class current-mode class-D CMOS power amplifier and digital envelope modulation technique for reduced spurious emissions. Issue 3 (23rd April 2013)

• Record Type: Journal Article
• Authors: Nakatani, Toshifumi; Kimball, Donald F.; Larson, Lawrence E.; Asbeck, Peter M.
• Editors: Nauwelaers, Bart; van Vliet, Frank E.; le Chevalier, François
• Is Part Of: International journal of microwave and wireless technologies. Volume 5:Issue 3(2013)
• Page Start: 271
• Page End: 284
• Publication Date: 2013-04-23
• Subjects: Power amplifiers, -- Buck converters, -- CMOS, -- Digital pulse width modulation, -- Polar transmitters, -- Dither; Wireless communication systems -- Periodicals; Microwave circuits -- Periodicals; Radio frequency -- Periodicals; 621.381305
• DOI: 10.1017/S175907871300041X
• Languages: English
• ISSNs: 1759-0787

Abstract

Abstract : A polar transmitter driven by digital input signals for envelope and phase is demonstrated, using a band-switching output resonator to achieve multiband operation. A new digital pulse width modulation algorithm is also shown to partially suppress spurious signals associated with the digital input envelope signal. The transmitter consists of a current-mode class-D (CMCD) CMOS power amplifier (PA), together with a buck converter with a dead-time generator for improved efficiency. The CMCD PA is tuned by band-switching capacitors that can handle up to 9 V, and is measured to have approximately 30 dBm output power with 31–35% drain efficiency under single-tone testing. The proposed spurious signal reduction technique works to partially suppress quantization noise without increasing power consumption. Overall efficiencies of 27.1/25.6% are obtained at 30.2/28.9 dBm continuous wave (CW) output powers and 0.85/1.75 GHz carrier frequencies, respectively. Spur suppression of 9–10 dB peak is achieved when the proposed algorithm is applied with wideband code division multiple access (WCDMA) modulation.