K-band Integrated Low-noise Receiver Components

The front-end circuit is a very important part in satellite communication systems. In this paper, we design some key circuits of the K-band front-end circuit,including the waveguide-to-microstrip transition, a low noise amplifier,a image-reject band-pass filter,a mixer and a low-pass filter.The system designed in this paper has a gain up to 29 dB and the noise figure is less than 2dB. The size of the overall circuit is 77.3mm×16.7mm,achieves the index of integrated.In this paper,two kinds of K-band waveguide-to-microstrip transitions are analyzed and designed.They are all done with the coaxial probe.The experimental results show that both the two transitions, the insert loss is less than 0.06dB.By choosing HEMT and a MMIC, we design a high gain, low noise LNA.The LNA finally designed has the characteristic of low noise figure less than 1.1dB,high gain more than 39dB,gain flatness less than 1 dB. The parallel-coupled microstrip image-reject filter achieves attenuation more than 60dB in the image frequency while the return loss up to 14dB in 19 GHz～21 GHz.In this paper, a single-balance mixer with Scotty diode from the company Skyworks is designed.The paper gives the design process and results of the mixer.Conversion loss of the mixer is less than 8.7 dB.The port isolations are up to 20 dB.Agilent ADS and HFSS are used to design, simulate and optimize the circuits. From the results of the testing, we can find that the circuits satisfies the design demands.