Electronically delivered or downloadable register-transfer level (RTL) code for use in design and development of transmitters including transmitters for wireless devices; RTL embodiments of circuitry for wireless devices and hardware including mobile handsets and base stations; Electronically delivered or downloadable RTL code for use in design and development of signal processors including a digital signal processor (DSP) or digital predistortion (DPD) processor for use in transmitters including transmitters for wireless devices; Register-transfer level (RTL) embodiments of circuitry for wireless devices and hardware including mobile handsets and base stations; Electronically delivered computer code to generate and/or manage coefficients used by a digital signal processor (DSP) or digital predistortion (DPD) processor to improve efficiency/performance of radio frequency transmitters; Electronically delivered computer code to generate and/or manage coefficients used by a digital signal processor (DSP) or digital predistortion (DPD) processor to improve efficiency/performance of radio frequency transmitters including wireless transmitters for use in mobile handset and base stations; Power management circuitry for use with digital supply modulation systems implementing discrete supply modulation to improve efficiency of wireless devices such as wireless transmitters; Wireless devices; Wireless transmitters for use in mobile handset and base stations; mobile handsets; base stations and access points; cellular networks; Radio frequency (RF) devices; Electronic communications systems comprised of computer hardware and recorded software for the transmission of data between two points; Downloadable application programming interface (API) software; Telecommunications transmitters; Broadband wireless equipment, namely, telecommunications base station equipment for cellular and fixed networking and communications applications; Telecommunication base stations; Semiconductor chip sets; Computer chips