IMPROVED UHF POWER TRANSISTORS IN MOSFET IC-TECHNOLOGY FOR PORTABLE RADIO APPLICATIONS

A power device for ultra high frequency use has been designed and fabr icated in a standard 1.3 mu m CMOS technology. A cell-based design is described for a compact and efficient power transistor layout. Devices with three different channel lengths (L = 1.1, 1.5 and 1.9 mu m) were compared in the study. Breakdown voltage of > 18 V was achieved by ad justing the channel doping profile. On-resistance measures indicated R (ON) similar to 1-2 Omega for a 1 W estimated power output device. f(T ) of up to 3.6 GHz and f(max) up to 10.5 GHz were extracted from small -signal s-parameter measurements. During class A measurements at 900 M Hz, power gain of 7.8 dB for L = 1.5 mu m devices and 9.5 dB power gai n for L = 1.1 mu m devices at V-d = 6 V were measured. Some devices we re even able to deliver 11 dB power gain at moderate power levels (20 dBm). Maximum efficiency was around 40% and saturated output power was estimated to 24-25 dBm (250-300 mW) for the largest studied device (W /L = 2800/1.1).