Reduced gain variation against temperature with thermistor on HPA module for W-CDMA system
A high-power amplifier (HPA) module for wide-band code division multiple access (W-CDMA) system with small gain variation against temperature is presented in this paper. Two temperature compensation techniques, which contain gain control bias circuits that correspond to temperature or thermistors were investigated. Comparison between the above techniques indicated that the technique with thermistors was more effective in reducing gain variation without affecting linearity. A fabricated two-stage HPA module for W-CDMA system with a thermistor in its input matching network provided a small gain variation within plusmn1 dB and an ACLR under -36 dBc in the temperature range from -10 to +85degC when ACLR was measured under load mismatched conditions, VSWR=1.4:1.
Low-Distortion Silicon Thermistor with Negative Temperature Coefficient of Resistance
A low-distortion silicon thermistor with a negative temperature coefficient of resistance (TCR) is demonstrated. The negative TCR is characterized by a freeze-out region in temperature-resistivity characteristics associated with deep levels in gold-doped silicon. A practical thermistor constant above 3000 K is obtained for p-type silicon, and excellent linearity in the I- V characteristics is exhibited bY measuring the distortion factors which exceed 80 and 100 dB for the second and third harmonic distortions, respectively. These values are as good as those (> 100 dB) for commercial oxide thermistor.
Frequency selective surface design for blinds applications
In this paper, the reconfigurable blind structure with frequency selective surfaces(FSS) for the building applications are presented. Frequency transmission characteristics for different angles of the proposed blind-FSSs are investigated and verified through simulation and measurement. The simulation results show that we can implement the reconfigurable blind-FSS for multiband wireless applications. To verify the proposed paper, two kinds of blind-FSSs, crossed dipole FSS and circular ring FSS are fabricated and measurements are performed for different angles. The proposed structure in this paper which is very simple, can be easily applied to any planar surface for wireless security applications at low cost.