GaN C-Band HPA for Phased-Array Applications
In the UMS GH25-10 GaN MMIC technology a C-band high power amplifier (HPA) has been realized. The current design is primarily intended for use in a space-based SAR system with a center frequency of 5.4 GHz and a sweep bandwidth of 100 MHz. To enable reuse of the amplifier in other radar systems such as weather radar, a large bandwidth is required. A design bandwidth from 5 to 6 GHz has been used. Simulation and measurement data from on-wafer and mounted samples will be shown. Showing more than 50 W output power with 45% efficiency the HPA shows sufficient performance to be used in a module for state-of-the-art active electronically scanned arrays. The measured output power and efficiency are a record for MMIC amplifiers.
20W S-band high power amplifier using stacked FET topology
Power amplifiers based on stacked Field Effect Transistor (FET) stages are often applied in silicon based technologies. The application of stacked FETs in Gallium Arsenide (GaAs) power amplifiers potentially leads to Monolithic Microwave Integrated Circuits (MMIC) devices with increased output power per chip area due to the efficient power combining. Furthermore the increased supply voltage results in lower supply currents. In this paper the design and results of a 20 W S-band High Power Amplifier (HPA) are given. Stability and thermal aspect are addressed and the experimental results show an output power in excess of 20 W with a peak Power Added Efficiency (PAE) of more than 40 %.
Evaluation of Impact of Yarn Count and Stitch Length on Pilling, Abrasion, Shrinkage and Tightness Factor of 1 ? 1 Rib Cotton Knitted Fabrics
This study investigates the impact of yarn count and stitch length of 100% cotton knitted fabrics. 1 × 1 ribs structured fabrics were used in this research work. The stitch length 2.50 mm, 2.52 mm, 2.60 mm, 2.70 mm, 2.80 mm and 2.96 mm were used of the yarn count of 26Ne, 28Ne and 36Ne. The areal densities of the grey fabrics were in various amounts. The impacts of yarn count and stitch length were measured concerning pilling resistance, abrasion resistance, and shrinkage and tightness factor. The result showed that the fabric pilling grade decreased while number of cycle increased. Abrasion resistance decreased but length wise shrinkage increased despite the fact that the stitch length increased. The results also exposed that the tightness factor of the fabric increased with the increase of the stitch length in both dyeing and washing state and finished state compared to grey state for the yarn count 26Ne and homogeneous result not found for yarn count 28Ne and 36 Ne. Evaluation of Impact of Yarn Count and Stitch Length on Pilling, Abrasion, Shrinkage and Tightness Factor of 1 × 1 Rib Cotton Knitted Fabrics