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This paper describes the design, fabrication, and testing of a DC-3 GHz ultra-wideband low-noise amplifier (LNA) using Avago ATF-54143 enhanced-mode pseudomorphic high-electron mobility transistor. Negative feedback network is introduced to ensure unconditional stability of the LNA over the full waveband. Simulation results show that the LNA provides a gain varying between 14.872 and 14.052 dB, a noise figure (NF) of less than 2.2 dB, and voltage standing wave ratios (VSWRs) approaching 2. A high simulated output third-order intercept point (OIP 3 ) of >30.2 dBm is achieved. In contrast, in 1-dB bandwidth of DC-3 GHz, the measured gain is nominal at 13.10 dB. The obtained NF changes in a small range of 2-2.178 dB, and the measured VSWRs are no more than 1.64, which are better than obtained from simulation results. At the same time, OIP 3 at 1, 2, and 3 GHz is 30.3, 29.13, and 29.34 dBm, respectively, while the output at the 1-dB compression point (P 1dB ) is 15. 43, 14.83, and 14.33 dBm, respectively.

This paper consolidates the activity of design and fabrication of 2.9-4.32 GHz, 4.3-6.42 GHz, and 6.4-8.4 GHz filter bank. Novel compact microstrip bandpass filters with stub-loaded multi-mode resonators are proposed. Simulated results indicate that all the filters exhibit insertion losses less than 1.5 dB with passband ripples of 1 dB and sharp attenuations of above 40 dB in their stopbands. The maximums of input and output VSWRs are 1.742 and 1.734, respectively. Due to fabrication error, the initial measured passbands show frequency shifts and insertion losses in upper passbands deteriorate seriously. After tuning of the filter bank, measured results imply that the input and output VSWRs are found lower than 2.135 and 2.187, and the insertion loss in 1 dB bandwidth is less than 2.52 dB. Filter bank has a sharp skirt and out-of-band rejection levels approaching to 40 dB in all desired stopbands except at the frequencies near 2f0.

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