Ku-band Monolithic Low Noise Amplifier Research

This paper deals with the process of Ku band 13.5～14.5GHz pHEMT transistor three-stage MMIC low noise amplifier's design and research. The principles and the design ofthe circuits was introduced. To improve the circuit's performance, a novel feedbackconfiguration was presented, achieving a better result.A three-stage low noise MMIC amplifier with on-chip matching network has beendemonstrated using 0.25um gate length GaAs pseudomorphic high electronic mobilitytransistors. The input stage was designed to provide a low noise figure, and the inter-stagesand output stage were matched to 50 ohm. First a conventional method was introduced todesign the circuit. The author designed the first stage with inductive series feedback atsource improving the circuit's stability and making the input matching easily. Then thethree-stage amplifier was made by cascading three identical stages. To improve thecircuit's performance, several feedback networks was experimented, and a novel feedbacktopology was presented. A feedback networks consisting of a resistance and a capacitancein series was added at the second and third stage's sources, the first stage as the same as theconventional method. This method improve the circuit whole performance largely,providing gain 28.2±0.25dB, noise figure 1.9dB, input and output VSWR 2.0:1 and 1.3:1respectively. Significantly, the noise figure of the circuit was not depravation. This noveltopology can be used in designing low noise MMIC amplifier.A Ku band 13.5～14.5GHz monolithic three-stage low noise amplifier employingfeedback networks has demonstrated. It achieves a noise factor of less than 1.9dB, a gainof more than 28 dB with flatness of less than±0.25 dB, an input and output VSWR lessthan 2.0:1 and 1.3:1 respectively across the band. The results show that it achieves therequirement of design objective.