Research Of Ku Band Low-Noise Amplifier

With the rapid development of satellite communication technology, the research of mobile satellite TV receiving system has received extensive attention. And as the front end of its receiving system, low noise amplifier’s performance determines the quality of the entire receiving system performance. According to the actual needs of subject, this paper designs two new low noise amplifiers respectively by using the discrete components circuit and MMIC integrated circuit.The Ku band low noise amplifier designed by discrete circuit is a two-stage structure, and its core of amplification component is the excellent chip VMMK-1225(PHEMT) of AVAGO company. The input stage of the first-stage amplifier is designed according to the minimum noise coefficient matching, and the output stage is designed according to the maximum gain matching. The two stages of whole circuit use the same circuit structure to cascade directly through the short microstrip line. This paper simulates and optimizes the design of amplifier though the microwave simulation software ADS, and the final noise coefficient is less than0.23dB, gain is greater than31dB, gain flatness is less than0.6dB, input/output standing wave ratio is less than1.6, which satisfy the requirements of the design index.The Ku band low noise amplifier accomplished by MMIC integrated circuit, uses three stages circuit matching to realize and chooses0.25μm HEMT GaAs process. The input stage of the entire circuit design is according to the minimum noise to match, the output stage according to50Ohm standard impedance to match. This paper adds spiral inductors in the source-level tube which introduce a series of negative feedback to realize the stability of the circuit. Three stages circuit structures are the same, and they constitute the overall MMIC amplifier by the way of direct cascades. After the commissioning and optimization, in11.7-12.5GHz,the finally realized Ku-band monolithic low noise amplifier noise figure is less than2.0dB, gain is greater than28dB, gain flatness is less than1dB, input VSWR is less than2.0,output VSWR is less than2.0, so the amplifier’s performance is good and in line of the requirements of the design specifications.