Design of a novel dual-band low noise amplifier incorporating dual-band impedance transformer

This paper reports the design of a novel flexible dual-band frequency dependent complex load impedance transformer. The proposed dual-band impedance transformer (DBIT) is capable of matching any arbitrary complex impedance seen by the active device at two arbitrary frequencies to a real source impedance of 50 Ω simultaneously. The closed form equations are derived analytically to achieve realizable solutions for arbitrary frequency band ratios. In order to validate the analysis, a dual-band impedance transformer operating at 2.4/5.2 GHz is fabricated and demonstrated. The proposed design approach is then applied to the design of a dual-band low noise amplifier for Ku and K band applications at 12 and 24 GHz respectively. The proposed low noise amplifier has gains of 15.82 dB and 12.8 dB, and noise figure of 0.48 dB and 1.13 dB at the two operating frequencies, respectively, which proves the feasibility and versatility of the transformer.