RF power transistors offer high efficiency and power density

June 15, 2012 // By Paul Buckley
NXP Semiconductors is expanding their eighth-generation (Gen8) LDMOS RF power transistor portfolio for wireless base stations, featuring excellent linearized efficiency, gain and wideband capability.

Covering all main cellular frequency bands between 700 to 2700 MHz, the latest version of NXP’s proven LDMOS process increases the efficiency of Doherty amplifiers by as much as three points and improves gain by as much as 1 dB.  The Gen8 LDMOS RF power transistors offer up to 115 MHz of signal bandwidth to enable full-band operation for all cellular frequency bands, including GSM, W-CDMA and LTE, as well as unprecedented video bandwidth up to 300 MHz.

Designed for cost-sensitive applications, the new Gen8 LDMOS transistors offer P1dB powers up to 270 W in SOT502-sized packages, and 400 W in SOT539-sized packages. The breakthrough power density of NXP’s Gen8 LDMOS transistors helps to reduce the size and weight of Doherty amplifiers – and ultimately the base station cabinet – significantly. Combined together, these enhancements also reduce total expenditures related to cooling and operation. Engineering samples of 17 product types are now available.  

Developed in close collaboration with key customers, NXP’s Gen8 LDMOS claims to enable best-in-class manufacturing yields for power amplifiers. The Gen8 transistors achieve excellent product consistency through a design that uses less sensitive matching topologies, and places resonance frequencies of the matching networks outside the band to limit the impact of manufacturing variations on performance. During manufacturing, the production line is calibrated on resonance frequency before the start of each batch. During testing, binning (gain and phase) is possible for sensitive Doherty designs, with several options available to increase correlation with the application, including Doherty testing for asymmetric transistors.