How to Design a 9-11 GHz Balanced Low Noise Amplifier using HJFET Transistor

Authors

1 Faculty of Electrical and Computer Engineering, Isfahan University of Technology (IUT), Isfahan, Iran

2 Research Institute for Avionics, Isfahan University of Technology, Isfahan, Iran

Abstract

Balanced amplifiers, using two quadrature couplers in their structures, are usually used in microwave integrated circuits for high power or low noise and wide-band applications. For an instance, the balanced amplifiers are appropriate for transmitters/receivers of large phased array radars used in air and space radar systems. In this paper, several microwave power combiners/dividers such as Lange coupler, Wilkinson power divider and branch-line coupler are used to design and simulate a balanced low noise amplifier (LNA) and then the results are compared with single-ended low noise amplifier. The balanced low noise amplifier with two-stage Wilkinson power divider/combiner is preferred to other circuits regarding to noise figure, frequency bandwidth, stability and easy implementation. The measurement results of the fabricated balanced LNA show that the gain is 12 dB with the flatness of ±0.5 dB over the frequency range of 9-11 GHz. In addition, the input and output return losses are more than 15 dB and 10 dB, respectively. The noise figure, measured by Y-factor method, is 1.3 dB at 10 GHz.

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