A single‐input single‐chain dual‐band power amplifier for CDMA mobile application

Abstract

SMF-28 fiber, HNA-TEC fiber could relax tolerances of misalignment. Based on the level of 1-dbm degradation, the transverse offset tolerance ranges are list in Table 2. After heating for more than 10 min, the offset range is increased at the speed of about 0.073 m per minute of heating time. The tolerance ranges of transverse misalignment between laser and HNA-TEC fiber were 5.4, 8.7, and 9.2 m for heating times 10, 30, and 60 min, respectively. The tolerance range enlarges to 12.5%, 81.3%, and 91.6%, as compared to that of SMF fiber. At the same condition comparing to SMF-28 fiber, a HNA-TEC fiber after 30 min heating increases about 50% for longitudinal tolerance range of misalignment, as shown in Figure 4(b). Since there is no treatment for all fiber tips, a resonance phenomenon appeared between the LD and the fiber tip when we took the power by moving the fiber in the longitudinal direction. Though the data varied during our experiment, the trend could be easily caught. These experimental results indicate that the HNA-TEC fiber offset tolerance width of misalignment could be enlarged without remarkably increasing the coupling loss. Wider tolerance required longer a heating period. However, for mass production, long-period processing for more than 30 min is not permitted. The tolerance increase rate becomes an important issue in fabrication consideration. In Table 2, the tolerance ranges per minute are given. The heating period from 10 to 30 minutes is better than the others. CONCLUSIONIn this paper, HNA-TEC fiber was fabricated and demonstrated in an LD coupling system. The MFR was expanded at the rate of 0.067 m/min at 1100°C heat treatment. For a 30-min HNA-TEC fiber, the transverse and longitudinal coupling tolerance of misalignment compared to SMF-28 fiber was enlarged by about 81% and 50%, respectively. The measured characteristics of our HNA-TEC fiber are feasible not only to realize a high-tolerance laser package, but also to reduce the assembly cost effectively. ABSTRACT:We demonstrate a new structure of the single-input single-chain power amplifier for cellular (850 MHz)/PCS (1750 MHz) dual-band operation. The single-input structure seems adequate for the reconfigurable multiband transmitter and the single-chain structure can achieve a small chip and module size, thus reducing manufacturing costs. This two-stage amplifier has a maximum output power of 30 dBm (29 dBm), a power-added efficiency (PAE) of 42% (37%), and an adjacent channel power ratio (ACPR) of Ϫ51 dBc (Ϫ48 dBc) at the output power of 28 dBm (28 dBm) under 3.4-V operation voltage for cellular (PCS) band. Figure 5 (a) Magnitude of Z_Cell and Z_PCS; (b) measured P out and PAE for cellular frequency Figure 6 Photograph of the two-stage power amplifier (0.960 ϫ 1.157 mm) Figure 7 Measured P out and PAE: (a) cellular; (b) PCS