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; Power management circuitry for use with digital supply modulation systems implementing discrete supply modulation to improve efficiency of wireless devices 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; Computer hardware for telecommunications; Computer hardware, namely, wireless access point (WAP) devices, wireless network extenders, and wireless network repeaters; Downloadable middleware for software application integration; Electronic communications systems comprised of computer hardware and recorded software for the transmission of data between two points; Computer networking hardware; Downloadable application programming interface (API) software; Circuit boards; Integrated circuits; Printed circuit boards (PCBs); Modems; Power amplifiers; Electrical power supplies; 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; Computer hardware, namely, wireless network extenders; Computer hardware, namely, wireless network repeaters