A 33W average output power Doherty power amplifier (PA) for 2.6GHz band was developed using compact package advanced GaN HEMTs which have Cds reduced 20%. A small-footprint Doherty network was successfully designed with plain small signal analysis, and the method was very practical. The Doherty PA exhibited a saturation output power of 52.5dBm (178W) and a saturated drain efficiency of 65.6%. The Doherty PA also achieved a drain efficiency of 55%, an ACLR of -52.8dBc and a power gain of 13.8dB at the average output power of 45.2dBm (33W) with 4-carrier W-CDMA signal at 2.6GHz using commercially available digital pre-distortion system. These excellent performances show good suitability for 2.6GHz band basestations (BTS), for example, W-CDMA, LTE and WiMAX, and small-sized circuit structure contributes to realize compact remote radio head type of BTS.

No abstract

A 240 W power FET for cellular base stations of a next generation system has been developed. The FET consists of four 60 W chips, which were fabricated by using our high efficiency and low distortion device technique, combined in a push-pull configuration. The developed FET achieved 240 W (53.8 dBm) output power, 11.2 dB linear gain and 54 YO power-added efficiency at 2.14 GHz. This is the highest output power device using GaAs FET technology. 0-7803-5687-X/00/510.00 0 2000 IEEE 2000 IEEE M?T-S Digest

No abstract

Deep-etching technology, which is a very simple fabrication process and requires only one lithography and one etching step without any regrowth, is applied to realize 1.5–1.55 µm wavelength GaInAsP/InP vertical grating (VG) distributed reflector (DR) lasers, which consist of a distributed feedback (DFB) region with the VG and a high-reflectivity distributed Bragg reflector (DBR) region. First, the coupling coefficient of the VG is theoretically estimated and fundamental lasing characteristics of the VG-DR lasers are investigated. Then, the fabrication process of the VG-DR lasers and the experimentally achieved fundamental lasing characteristics are given. A threshold current of 12.4 mA and a differential quantum efficiency of 42% from the front cleaved facet are achieved for a 220-µm-long and 5-µm-wide device. A submode suppression ratio (SMSR) of 33 dB at a bias current of 2.4 times the threshold is obtained.