Title :
A 700-W peak ultra-wideband broadcast Doherty amplifier
Author :
Qureshi, J.H. ; Sneijers, W. ; Keenan, R. ; deVreede, L.C.N. ; van Rijs, F.
Author_Institution :
NXP Semicond. Nijmegen, Nijmegen, Netherlands
Abstract :
A wideband high-power Doherty design technique enabling fractional bandwidths > 50% is described. It utilizes wideband impedance inversion, device output capacitance compensation and passive phase-optimized wideband input-signal splitting. As prove of concept a LDMOS based ultra-wideband broadcast Doherty amplifier is presented, which covers the UHF-TV 470MHz-803MHz (BWrel = 52%) band with average efficiencies between 38%-47% @Pavg > 115W while maintaining peak power capability > 700W over the entire band. Predistortability is demonstrated by satisfying the digital TV linearity requirements (-38dBc) using a commercial DVB-T exciter. The proposed DPA is an excellent drop-in replacement for the low-efficiency wideband PA blocks currently in use in broadcast transmitters.
Keywords :
UHF power amplifiers; digital video broadcasting; radio broadcasting; radio transmitters; LDMOS; broadcast transmitter; digital TV linearity; frequency 470 MHz to 803 MHz; high power Doherty design technique; optimized wideband input signal splitting; output capacitance compensation; passive phase input signal splitting; power 700 W; ultrawideband broadcast Doherty amplifier; wideband impedance inversion; Capacitance; Impedance; Power amplifiers; Power generation; Transmission line measurements; Transmitters; Wideband; Broadcast Amplifiers; Doherty; Power Amplifiers; Wideband Amplifiers;
Conference_Titel :
Microwave Symposium (IMS), 2014 IEEE MTT-S International
Conference_Location :
Tampa, FL
DOI :
10.1109/MWSYM.2014.6848495
