Ka-band Broadband Monolithic Low Noise Amplifier

As one of the key devices in the millimeter-wave integrated receving front-ends, theperformance of the Ka band low noise amplifier play a critical roles for the wholeperformance of the modules.This paper mainly introduces the circuit design and simulation results of the Kabroadband MMIC LNA. Using 0.25μm HEMT process and based on the design index, thematching circuits, bias and stability circuits as well as topology structure are all designed.Simulation and optimization of the circuits are under the Agilent ADS software.The Ka broadband MMIC LNA designed in this paper used a three-stage structure inthe circuit. Each stage with the same structure which have matching network at both theinput and output ports are designed with different design objective to achieve particularperformance. With the requirement of broadband here, the matching networks are all usedthe T-type matching network. Moreover, with the convenient of cascade connection, theinput and output ports are all matched to 50Ω. After each stage achieve requiredperformance, cascade of three-stage circuits proceed optimization. Finally, the bandwidthof the circuit was broadened by the inclusion of suitable short circuit stubs at the input andoutput ports.The Ka broadband MMIC LNA designed here exhibits a good performance over theworking band, it achieves a noise factor of less than 3.4 dB, a gain of over 22 dB withflatness of less than±0.5 dB, and good VSWR of less than 2 dB. The results show that itcompletely achieves the requirement of design objective.